Session 3aAA Architectural Acoustics: Measurement and ... · Session 3aAA Architectural Acoustics:...

WEDNESDAY MORNING, 20 MAY 2009 GRAND BALLROOM II, 8:55 A.M. TO 12:00 NOON

Session 3aAA

Architectural Acoustics: Measurement and Modeling of Scattering Effects

David T. Bradley, ChairPhysics and Astronomy Dept., Vassar College, Poughkeepsie, NY 12604-0745

Invited Papers

8:55

3aAA1. Scattering prediction and measurement in architectural acoustics. David T. Bradley �Phys. and Astron. Depart., VassarCollege, 124 Raymond Ave., Poughkeepsie, NY 12604-0745, [email protected]�

Reflected sound energy typically exhibits a combination of both specular and diffuse behavior when acoustic waves encounter asolid surface. For specularly reflected sound, the angle of reflection is equal to the angle of incidence. A diffusely reflected sound ischaracterized by dispersion in both the spatial and temporal domains. The ability of a surface to diffusely reflect sound is characterizedby the amount of scattering in its reflected energy, and can be determined using numerical prediction schemes and experimental mea-surement techniques. Although the study of scattering surfaces plays an integral role in several fields of acoustics, the development ofthese measurement and prediction procedures is relatively nascent, particularly in the field of architectural acoustics. An overview of thecurrent state-of-the-art for these procedures will be presented along with an outline of possible future directions in this area of research.

9:15

3aAA2. Measurement and modeling of scattering in underwater acoustics: A potential value to architectural acoustics? MartinSiderius �Dept. of Elect. and Comput. Eng., Portland State Univ., 1900 SW 4th Ave., Portland, OR 97201, [email protected]�, DavidBradley �Vassar College, Poughkeepsie, NY 12604-0745�, and Lisa Zurk �Portland State Univ., Portland, OR 97201�

Scattering measurement and modeling techniques in underwater acoustics have undergone significant progress through several de-cades of research. The knowledge gained from this research can be applied to similar scattering problems found in above water systems,such as those typically seen in architectural acoustics. Underwater environments have inherently complex scattering behavior includingmultiple propagation paths and boundaries that are rough and spatially variable. Additionally, boundaries are often moving, which canintroduce different Doppler shifts on multipath arrivals, referred to as Doppler spread. These complications make modeling underwaterpropagation and scattering a challenging problem. However, there are currently several models that are routinely used for predictingunderwater acoustic behavior. In some cases, deterministic modeling can be used while in others the complexity only allows for astatistical description of the acoustic field. In recent years, acoustic communications have emerged as an important ocean application,and the innovations provided by these systems have pushed the limits of current techniques. An overview of these modeling and mea-surement techniques will be presented, and the lessons learned from recent advances will be reviewed in the context of identifyingcommonalities between underwater and architectural acoustics.

9:35

3aAA3. Fractal surfaces: Generation and acoustic scattering prediction. Derek R. Olson and David T. Bradley �Phys. and Astron.Dept., Vassar College, 124 Raymond Ave., Box 2529, Poughkeepsie, NY 12604�

Typical acoustical diffuser design results in diffuse sound scattering only for a limited frequency band, which is problematic giventhe breadth of the human audible frequency range. Surfaces exhibiting fractal geometries may address this problem due to their self-similarity over multiple scales. Stochastic fractals, such as the random midpoint displacement �RMD� fractal, are well-suited to thisusage since they can be mapped onto physical surfaces appropriate for acoustical diffusers. In the current project, virtual RMD fractalsurfaces were generated and then constructed using a 3-D printer. A pilot study has been conducted to determine the scattering propertiesof the fractal surfaces using a numerical prediction scheme carried out using the boundary element method �BEM�. Experimental mea-surements of the scattering properties were also carried out according to ISO 17497. The numerical predictions and experimental mea-surements were contrasted to improve numerical prediction accuracy and optimize the fractal design parameters of acoustical diffusers.These parameters include surface roughness, fractal dimensionality, number of iterations, and the random number probability distribu-tion function. The comparison of the numerical and experimental results will be presented along with effects of the fractal designparameters.

9:55

3aAA4. A suggested method to be used to measure the scattering coefficient of full-scale samples. Ron Sauro �NWAA Labs., Inc.,25132 Rye Canyon Loop, Santa Clarita, CA 91355, audio�[email protected]�

In attempting to follow ISO 17497-1 as a method for measuring full-scale scattering coefficients, it was observed that many of therecommended steps needed to be modified for those full-scale measurements. Variations were tried to aid in these measurements. Thesevariations are described and suggested solutions to the problems observed are presented. It was observed that continuous rotation of thesample, rather than step action rotation, worked better for taking consistent data from the sample. A stable chamber environment is alsonecessary with humidity reaching at least 50% and temperature variations should not vary by more than 1°C throughout all four parts

2613 2613J. Acoust. Soc. Am., Vol. 125, No. 4, Pt. 2, April 2009 157th Meeting: Acoustical Society of America

of the test. It was also observed that a less directional source than recommended was needed so two dodecahedron loudspeakers werechosen to reproduce a combined weighted noise stimulus source. Six data microphones were placed at random locations and varyingheights to collect data. Data were compared between the suggested method and the ISO-17497-1 standard.

10:15—10:30 Break

Contributed Papers

10:303aAA5. Investigating multifractals to quantify diffuseness in rooms.Noel W. Hart �Graduate Prog. in Archit. Acoust., Rensselaer Polytech. Inst.,2403 21st St. Apt. 5, Troy, NY, 12180, [email protected]� and Ning Xiang�Rensselaer Polytech. Inst., Troy, NY, 12180�

Diffuseness, an important room acoustics parameter, currently has no ac-curate objective method of quantification. Most methods that claim to beable to quantify it require specialized equipment or guesswork. Multifractalspresent a recent method that allows diffuseness in rooms to be quantified byanalyzing a single room impulse response �Loutridis, JASA 125�3� �2009��.This method will be verified by acoustical measurements in rooms of vari-ous degrees of diffuseness. Since this method has only been demonstrated insmall rooms, its applicability towards larger rooms of different types istested. Frequency dependency is also unknown and is investigated.

10:453aAA6. Prediction and tailoring of steady-state broadband sound fieldsin enclosures using absorption scaling and energy-intensity boundaryelements. Donald Bliss, Krista Michalis, and Linda Franzoni �Mech. Eng.and Mater. Sci., Duke Univ., Durham, NC 27708, [email protected]�

Enclosures with diffuse reflection boundaries are modeled with anenergy-intensity boundary element method using uncorrelated broadband di-rectional sources. An absorption-based perturbation analysis shows the spa-tial variation of acoustic field obeys certain scaling laws. A series expansionin terms of average absorption gives separate boundary integral problems ateach order. The lowest-order solution has a uniform level proportional to thereciprocal of the average absorption. The next-order solution is independentof average absorption and primarily responsible for spatial variation of theacoustic field. This solution depends on the spatial distribution of absorptionand input power sources, but not their overall level. For the primary spatialvariation, the effects of the relative distributions of absorption and inputpower are linear and uncoupled. These distributions can be expressed interms of constituent spatial modes corresponding to the ways absorption andinput power can be distributed. Solved numerically once for each mode, theacoustic field can be expressed in terms of the modal amplitudes in closedform. These amplitudes can be adjusted to tailor the spatial variation. Ex-amples include how to distribute absorption to minimize sound levels in onelocation, or how to achieve a uniform interior field. �Sponsor: NSF.�

11:003aAA7. Measuring the uniform diffusion coefficient: Synthesizedaperture goniometer measurements. Philip W. Robinson, Ning Xiang�Architectural Acoust. Program, Rensselaer Polytechnic Inst.�, and PeterD’Antonio �RPG Diffusor Systems, Inc.�

There are currently two methods to measure the diffusion/scatteringfrom acoustical surfaces: reverberation chamber measurement and in-situmeasurement using a semicircular array of microphones called agoniometer. Each of these methods has advantages and drawbacks. The re-verberation chamber method accounts for random incidence, but producesinconsistent results for materials of the same profile but different absorption.It does not distinguish between one-dimensional and two-dimensional sur-face topologies, since the sample is rotated, and is also inapplicable to highabsorption materials. The goniometer measurement quantifies directivity aswell as diffusion, but presents challenges related to processing power, asmany microphones are required to achieve reasonable resolution. Using aprocedure akin to synthesized aperture radar, a 2.5° resolution polar plot ofthe 180° response is achieved by scanning eight microphones rather thanemploying a full array of 72. Also, since the direct sound and reflected

sound arrive at the receiver in close succession when measuring low inci-dent angles, special processing must be exercised in order to resolve the re-lationship between the sounds. This research addresses the challenges of thegoniometer measurement and attempts to use a synthesized aperture goni-ometer to derive accurate diffusion and directivity properties of materials.

11:153aAA8. Measurement and improvement of the diffuse-reflectioncoefficients of profiled-wood surfaces. Chris Bibby and Murray Hodgson�Acoust. & Noise Res. Group, SOEH-MECH, Univ. of British Columbia,3rd Fl., 2206 East Mall, Vancouver, BC, V6T 1Z3 Canada�

An apparatus and procedure were developed for measuring the diffuse-reflection coefficients of surfaces in an anechoic chamber according to theISO-17497 method. This involves determining the proportion of incoherentenergy in the impulse response measured in the presence of the surface. Sur-face absorption was measured by the reverberation-room method. Thesound-absorption and sound-diffusion properties of two existing profiled-wood architectural panels, one with sinusoidal corrugations, the other com-prising rectangular sections of different heights, were characterized. Inves-tigations into how to improve the absorption and diffusion characteristicswere made, and prototype surfaces tested and evaluated.

11:303aAA9. An in-situ diffusivity measurement method for diffuser design inconcert halls. Jin Yong Jeon and Yong Hee Kim �Dept. of ArchitecturalEng., Hanyang Univ., Seoul 133-791, Korea�

This study investigates an in-situ measurement method to evaluate thediffuseness of a sound field using scale model concert halls. The diffuserswere applied to scale model concert halls in which the impulse responses atboth the audience and stage area were observed. Both reflection number�RN� and reflection energy �RE� were used as in-situ diffusivity indices: RNis defined by the number of reflection rays of which critical amplitude levelis within �30 dB after the direct sound, and RE defined by the integratedenergy at the normalized impulse responses. Through the scale model mea-surements, it was observed that half of the side walls near the stage wereeffective for diffuseness of sounds both in auditorium and on stage. It wasalso found that the balancing of in-situ diffusivity is useful for diffusenessperception, which is subject to the level of the direct sounds.

11:453aAA10. Measurement of diffuse sound reflection from an impedancesurfaces using one microphone by bayesian inversion. Gavin Steininger�Acoust. and Noise Control Res. Group–Dept. of Mech. Eng., Univ. of Brit-ish Columbia, Vancouver, BC, Canada� and Murray Hodgson �Univ. of Brit-ish Columbia, Vancouver, BC, Canada�

This paper discusses the use of inverse methods to find the absorptionand diffusion characteristics of surfaces. An impedance surface in ananechoic chamber is excited by a pure tone source above it. The steady-statesound level is measured at n points above the impedance surface. The dis-tribution of the n steady-state sound-pressure levels is assumed to beGaussian. The set of mean or predicted values for this distribution is gener-ated by finding the modulus of a modified Sommerfeld boundary elementsolution to the Helmholtz equation. The modification is to add multiple dif-fusely reflected waves each of which is additionally attenuated by a distri-bution that is proportional to sin�2��G��D��H��D�, where G�� is thepiecewise function �G��/�Spec, ��Spec, and ��/2��/��/2��Spec

otherwise� and H��1��/��. The system of equations is then optimizedfor the specific impedance of the surface, the normal diffusion coefficient,and the azimuth diffusion coefficient �Z, D�, and D�� using Bayesian


inversion. This process is repeated for two surfaces �painted plywood over16 inch studs and painted plywood over 16 inch studs with randomly placed

wooden blocks� at six frequencies �250, 500, 1000, 2000, 4000, and 8000Hz�.

WEDNESDAY MORNING, 20 MAY 2009 GALLERIA NORTH, 8:00 TO 11.45 A.M.

Session 3aAB

Animal Bioacoustics and Acoustical Oceanography: Autonomous Remote Monitoring Systems for MarineAnimals III

Marc O. Lammers, ChairHawaii Inst of Marine Biology, Kailua, HI 96734

Invited Papers

8:00

3aAB1. From mysticete song to odontocete echolocation: Monitoring cetacean sounds with high-frequency acoustic recordingpackages (HARPs). Sean M. Wiggins and John A. Hildebrand �Scripps Inst. of Oceanogr., 9500 Gilman Dr. La Jolla, CA 92093-0205,[email protected]�

Marine mammals produce a wide range of sounds from 10s of Hz to 100s of kHz. To remotely monitor these various sounds withautonomous systems, instruments with wide bandwidths are required. A general purpose, autonomous, high-frequency acoustic record-ing package �HARP� is described that can record sounds ranging from low-frequency blue whale �Balaenoptera musculus� song tomid-frequency dolphin whistles and beaked whale sweeps to high-frequency dolphin clicks. In addition to monitoring marine mammals,sounds from fish, contributions from wind and rain, and anthropogenic sources such as ships and sonar also are recorded potentiallyallowing for the study of cetacean behavioral response to these sounds. HARPs have been deployed for periods of up to one year, invarious configurations such as standard moorings, seafloor packages, and arrays, and in remote locations including the Arctic, BeringSea, Gulf of California, around Hawaii, and offshore of Washington State and southern California. The various configurations of thesedeployments and the wide range of marine mammal monitoring data they have provided are discussed in addition to lessons learnedfrom these studies. �Work supported by the U.S. Navy CNO-N45.�

8:20

3aAB2. Extending passive acoustic capabilities of autonomous recorders by using multiple hydrophones. Aaron Thode, RobertGlatts �Marine Phys. Lab., Scripps Inst. of Oceanogr., 9500 Gilman Dr., San Diego, CA 92109-0238�, and William C. Burgess�Greeneridge Sci. Inc., Goleta, CA 93117�

Low-power data acquisition systems have attained sampling rates large enough to enable multielement hydrophone arrays to bedeployed autonomously, at the cost of reducing the individual sampling rate per phone. This paper discusses what theoretical advantagesbandlimited multielement recordings can provide over single-hydrophone data, including array gain for increased detection range, in-terfering noise source rejection, environmental inversion, and biological source tracking. These points are illustrated with data collectedfrom an autonomous four-element vertical array off Queensland, Australia in 2003, and data collected from an autonomous eight-element, 21 m aperture vertical array deployed at 35 m depth in the Beaufort Sea in 2008. These examples also provide insight into thetechnical and logistical challenges required by such deployments, including deployment and recovery systems that do not endanger orentangle array cables. �Work supported by NPRB, logistics provided by Greeneridge Sciences and Shell Co.�

Contributed Papers

8:403aAB3. An autonomous, near-real-time buoy system for automaticdetection of North Atlantic right whale calls. Eric Spaulding, MattRobbins, Tom Calupca, Christopher Clark, Tremblay Tremblay, AmandaWaack, Ann Warde �Bioacoust. Res. Prog., Cornell Univ., 159 SapsuckerWoods Rd., Ithaca, NY 14850�, John Kemp, and Kristopher Newhall�Woods Hole Oceanograph. Inst., Woods Hole, MA 02543�

A moored buoy system for automatic detection of endangered North At-lantic right whale �NARW� upcalls was developed to provide near-real-timeinformation on the presence of whales. The marine components include theWHOI buoy platform �mooring, hydrophone, power system, surface expres-sion, and antennae� and Cornell buoy electronics �housing, analog interfacehardware, GPS, embedded computer, detection engine, and telemetryhardware�. Shore-side Cornell components include telemetry equipment,

server hardware and processing software, database, and interfaces for dataannotation, access, and visualization. The buoy hardware/software system iscapable of capturing and ranking NARW upcall candidates as 2 s, 2000 Hzsampled audio clips. GPS location, timestamp, and other metadata associ-ated with each audio clip are bundled together and uploaded via satellite forprocessing. Human analysts regularly annotate incoming data, resulting in acurated database of NARW detections. Periodic “health and status” data al-low for confirmation that buoys are functional. Regular voltage reportinghelps predict required maintenance. Following initial implementations of thesystem in 2005, a series of successes and failures have led to systemimprovements. Deployments have progressed from prototype near-shoreunits to an operational network continuously monitoring the shipping lanesoff Boston to meet ship strike mitigation requirements. Upcoming featuresand capabilities will be discussed.


8:553aAB4. Right whale gunshot calls in the southeastern Bering Sea.Catherine L. Berchok, Laura J. Morse, Phillip J. Clapham �Natl. MarineMammal Lab., NOAA/AFSC, 7600 Sand Point Way NE, Seattle, WA98115-6349, [email protected]�, Holger Klinck, Karolin Klinck,David K. Mellinger �Oregon State Univ. & NOAA Pacific Marine Environ.Lab., Newport, OR 97365�, Donald K. Ljungblad �Marine Acoust. Consult-ants, LLC, Elk Mountain, WY 82324-0006�, Sue E. Moore�NOAA/S&T-PMEL, Seattle, WA 98115-6349�, Francesco Scattorin�Universita di Pavia, 27100 Pavia, Italy�, and Jennifer L. Keating�Zoological Society of San Diego, San Diego, CA 92112-0551�

The eastern population of the North Pacific right whale �Eubalaenajaponica� is critically endangered. Following extensive historical whaling inthe 19th century and large illegal catches by the USSR in the 1960’s, it is

likely that this population now numbers in the tens of animals. Little isknown about the distribution, movements, migrations, or habitat use of thispopulation, but the existing data suggest that it now occupies a reducedrange compared to historical times. In 2007, NMML began conducting amultiyear study of the distribution, abundance, and habitat use of North Pa-cific right whales in the North Aleutian Basin and southeastern Bering Seausing aerial and vessel surveys. During the 2008 survey, directionalsonobuoys were used 24 h a day to record right whale calls and obtain cross-bearings to the whales. Although previous work in the Bering Sea focusedon detections of the right whale upsweep call, our findings suggest that thegunshot call is much more ubiquitous. Spatial and temporal trends of gun-shot calls will be presented, and changes in gunshot call characteristics rela-tive to observed surfacing sequences will be described. �Work supported byan interagency agreement from the Minerals Management Service.�

Invited Paper

9:10

3aAB5. Environmental acoustic recording system (EARS) buoys for marine animal acoustics. George E. Ioup, Juliette W. Ioup,Arslan M. Tashmukhambetov, Lisa A. Pflug �Dept. of Phys., Univ. of New Orleans, New Orleans, LA 70148, [email protected]�, JoalJ. Newcomb �Stennis Space Ctr., MS�, Natalia A. Sidorovskaia �Univ. of Louisiana at Lafayette, Lafayette, LA�, Stan A. Kuczaj, Gray-son H. Rayborn, James M. Stephens �Univ. of Southern Mississippi, Hattiesburg, MS�, Christopher O. Tiemann, and Alan Bernstein�Univ. of Texas at Austin, Austin, TX�

EARS buoys were developed as autonomous, moored, underwater recording systems by the Naval Oceanographic Office�NAVOCEANO� to make long-term ocean ambient noise measurements. When the Littoral Acoustic Demonstration Center �LADC�was formed as a consortium of university and U.S. Navy scientists in 2001, the buoys were capable of measuring up to 1000 Hz for 1yr. LADC added listening to sperm whales to its noise and propagation measurements. NAVOCEANO quickly modified the buoys tomeasure up to 5859 Hz for 36 days. The buoys, moored at depths from 550 to 950 m in the Gulf of Mexico, produced exceptionallyclear recordings of sperm whale echolocation and coda clicks and recordings of other whales. EARS Generation 2 buoys are nowcapable of recording one channel to 96 kHz, or four channels to 25 kHz, for more than 13 days on four 120 Gbyte notebook disk drives.Experiments in the Gulf of Mexico and the Ligurian Sea have targeted both sperm and beaked whales. Audio results and visualizationsof these recordings reveal rich detail of Odontocete clicks and enable new analyses, such as the identification of individual whales fromthe properties of their clicks. �Research supported by ONR and SPAWAR.�

Contributed Paper

9:303aAB6. Localization to verify the identification of individual spermwhales using click properties. Juliette W. Ioup, George E. Ioup, Lisa A.Pflug, Arslan M. Tashmukhambetov �Dept. of Phys., Univ. of New Orleans,New Orleans, LA 70148, [email protected]�, Christopher O. Tiemann, AlanBernstein �Univ. of Texas at Austin, Austin, TX�, Natalia A. Sidorovskaia,Philip Schexnayder �Univ. of Louisiana at Lafayette, Lafayette, LA�, Joal J.Newcomb �Stennis Space Ctr., MS�, Stan A. Kuczaj, Grayson H. Rayborn�Univ. of Southern Mississippi, Hattiesburg, MS�, and Rowena M. Carlson�SPAWAR Systems Ctr. Pacific, San Diego, CA�

Previous research to identify individual sperm and beaked whales fromthe properties of their echolocation and coda clicks using cluster analysishas been reported. Although reasonably consistent and robust results show-ing distinct classes �each corresponding to an individual� have been obtainedwith both self-organizing maps and K-means, no independent verification of

these identifications has previously been available. However, data from aJuly 2007 experiment in the Gulf of Mexico should provide enough geom-etry information to verify some identifications. The Littoral Acoustic Dem-onstration Center deployed six environmental acoustic recording systembuoys, measuring to 96 kHz for 9 days, to record sperm and beaked whaleclicks in the northern Gulf of Mexico. Three buoys were in close proximityto enable multisensor detections of single clicks for possible localization,tracking, or bearing estimation sufficient to confirm the identification of in-dividuals from cluster analysis. Displays of cluster classifications versustime coupled with location estimates for the clicks give evidence of the ac-curacy of the identifications. Though localization serves to verify the clas-sification tool, click identification complements localization by separatingsounds from multiple sources when several whales’ clicktrains overlap, po-tentially enabling previously impossible tracking. �Research supported bySPAWAR and ONR.�

Invited Papers

9:45

3aAB7. Detection of killer whale presence using low duty cycle recorders. Jeffrey A. Nystuen �Appl. Phys. Lab., Univ. of Wash-ington, 1013 NE 40th St., Seattle, WA 98105, [email protected]�, M. Bradley Hanson, Candice Emmons �NOAA NorthwestFisheries Sci. Ctr., Seattle, WA�, Paul Wade �NOAA Alaska Fisheries Sci. Ctr., Seattle, WA�, and Jennifer Miksis-Olds �Penn StateUniv., State College, PA�

Passive aquatic listeners �PALs� have been developed to make long-term �up to a year� autonomous measurements of the underwaterambient noise in the marine environment. Because of data storage limitations and low-power requirements, PALs have a very low dutycycle, of the order of 1 percent. In fact, they are optimized for acoustic rainfall detection and have been successfully used to measurewind speed and rainfall rate at sea using spectral components of the sound field. These geophysical sounds have relatively long timescales �minutes� compared to vocalizations of marine mammals �seconds� or mooring noise �chain clanking�. Data collection was de-signed to detect and reject short temporal signals. However, these signals include marine mammal vocalizations. Consequently, thesampling strategy was modified to evaluate the temporal content of the data sample and save the temporal data sample only if it contains


a signal consistent with killer whale vocalizations. These sound bites have demonstrated detection of pod-specific vocalizations ofresident-type killer whales, transient-type killer whales, bone crunching from likely killer whale predation �eating� on sea lions, andhumpback and N. Pacific right whales.

10:05—10:25 Break

10:25

3aAB8. Managing the passive acoustics data deluge. David A. Mann �Coll. of Marine Sci., USF, 140 7th Ave. S., St. Petersburg, FL33701, [email protected]�

Passive acoustic recording systems can generate large amounts of data, especially given the increasing availability of inexpensiveflash memory. Thus it is easy to collect more data than can be efficiently analyzed. One approach to this problem is to minimize datacollection on the recorder by performing real-time automated detection of acoustic targets of interest. An alternate approach, where onedoes not know what signals may be present, is to record large amounts of data over extended periods of time. DSGlab is an open-sourcedatabase and data analysis system implemented with MATLAB that is designed to manage large amounts of raw data. The databaseaspect of the program allows querying of data by latitude, longitude, depth �or altitude�. Each recorded data file is tagged with headerinformation including lat/lon/depth, timestamp, sample rate, and calibration. The data analysis section processes the files according toa user-specified signal processing chain, which does not require a knowledge of programming to generate, and returns results to adatabase and to individual files. The results of signal processing can then be quickly browsed with the data viewer. The system isdesigned to allow inter-laboratory collaboration and data sharing.

Contributed Papers

10:453aAB9. Acoustic rediscovery of right whales in a former whaling area,the Cape Farewell Ground, between Greenland and Iceland. David K.Mellinger, Sharon L. Nieukirk, Karolin Klinck, Holger Klinck, Robert P.Dziak �Cooperative Inst. for Marine Resources Studies, Oregon State Univ.and NOAA Pacific Marine Environ. Lab., 2030 SE Marine Sci. Dr., New-port, OR 97365�, and Phillip J. Clapham �NOAA Natl. Marine MammalLab., Seattle, WA 98115�

The North Atlantic right whale �Eubalaena glacialis� is one of theworld’s most endangered cetaceans, with only 300–350 animals believedalive. Most right whales are thought to range from Florida to Nova Scotia,though the whereabouts of a significant portion of the population remainsunknown in both winter and summer. Here we describe an acoustic surveyfor right whales near the Cape Farewell Ground, a late 18th-century whalingarea. Continuously recording autonomous hydrophone instruments were de-ployed at five sites for one year in 2007–2008, after which data were ana-lyzed by automatic detection with manual checking for “up” calls of rightwhales. Over 2000 calls were detected in all, with calls found at all sites butmostly from near the Cape Farewell Ground. The data are consistent with aseasonal migration northeastward toward Iceland in July–August followedby return movement later in the fall, with the last detection in December. Atone site, calling occurred in the fall on 17 separate occasions, suggesting asignificant number of right whales present. A right whale photo-identified in2003 at the Cape Farewell Ground was not in the North Atlantic right whalecatalog, suggesting the possibility of a previously unidentified stock.

11:003aAB10. Sound production and behavior in an eastern North Pacifickiller whale population: Implications for autonomous remotemonitoring. Marla M. Holt, Dawn P. Noren, Candice K. Emmons �MarineMammal Program, NOAA/NMFS Northwest Fisheries Sci. Ctr., 2725 Mont-lake Blvd. East, Seattle, WA 98112, [email protected]�, and Anna-Maria Seibert �Univ. of Munich, Planegg-Martinsried, 82152 Germany�

Remote acoustic monitoring is often used to determine the seasonal andspatial distributions of vocal animals, particularly when conditions of othermonitoring approaches are limited. Additionally, sound production patternsmight be used to infer important activities of free-ranging animals in the ab-sence of other cues. Animals produce sounds during activities such as for-aging and breeding, but such patterns are expected to vary between species/populations that are based on a variety of ecological factors. For example,fish-eating killer whales are more vocally active than mammal-eating killerwhales, presumably since mammalian prey are sensitive to killer whalesounds. Southern Resident killer whales �SRKWs� are a fish-eating popula-tion found in coastal waters of Washington State and British Columbia. Thegoal of this study was to extend previous work on the behavioral correlates

of sound production in SRKWs. We collected behavioral and acoustic datasimultaneously over two field seasons and found that click occurrence aswell as calling rates �calls/whale/min� were significantly higher whenwhales were foraging compared to traveling. Such patterns are useful forinferring events from remote acoustic monitoring. These results also indicatethat communicative signals are particularly important during foraging activi-ties in this population and have implications for noise disturbance.

11:153aAB11. Simultaneous acoustic tag and seafloor acoustic recorderdetection of right whale calls in the Bay of Fundy. Susan E. Parks �Appl.Res. Lab., The Penn State Univ., P.O. Box 30, State College, PA 16804�,Christopher W. Clark �Cornell Univ., Ithaca, NY 14850�, Mark Johnson, andPeter L. Tyack �Woods Hole Oceanograph. Inst., Woods Hole, MA 02543�

Passive acoustic monitoring is playing a growing role in marine mam-mal detection. Determining the range of detection for calls of a particularspecies in a particular location is important to assess the regional coverageprovided by individual recording units. This study describes the comparisonof right whale calls recorded by digital acoustic recording tags �Dtags� at-tached with suction cups to North Atlantic right whales and the detection ofthe same calls using a dispersed seafloor array of autonomous recorders. Theseafloor array consisted of 5 units, spaced 6–10 km apart, continuously re-cording from July 29– August 17, 2005. Dtags were attached to a total of 14individual right whales during this time period and 7 of these individualsproduced a total of 88 tonal calls during tag attachment. The tag and relatedtracking of the whale provided information on call type, and the timing,depth, and approximate location of the whale producing the call. Taggedwhale calls were audible on the seafloor array, and whale-recorder distancesprovided estimates of the acoustic detection range for right whales in theBay of Fundy, Canada.

11:303aAB12. Annual variability of cetacean occurrence along the northeastcoast of Iceland measured using ecological acoustic recorders. E.E.Magnusdottir, M.H. Rasmussen �Husavik Res. Ctr., Univ. of Iceland, Haf-narstett 3, 640 Husavik, Iceland, [email protected]�, and M.O. Lammers �HawaiiInst. of Marine Biology, Kailua, HI 96834�

In order to continuously monitor the annual density and habitat use ofcetacean species at the NE coast of Iceland, we deployed two seabedmounted ecological acoustic recorders �EARs� in Skjalfandi Bay �66 deg 05.929 N, 17 deg 25.262 W; 66 deg 03.070 N, 17 deg 39.811 W�. The EAR isa microprocessor-based autonomous recorder. Each EAR was programmedto record for 1 min every 15 min. Both EARs will be retrieved every 3–5months during a 1-year period. A custom Matlab program will be used toautomatically detect and analyze target sounds. Target biological sounds re-


corded are primarily those produced by cetaceans and also by pelagic fish.Blue whales �Balenoptera musculus�, humpback whales �Megapteranovaeangliae�, minke whales �Balaenoptera acutorostrata�, white-beakeddolphins �Lagernorhynchus albirostris�, and killer whales �Orcinus orca� arewell known to visit Skjalfandi Bay. In addition, it has been suggested that

cod �Gadus morhua� is spawning in the bay in spring time. The results couldreveal annual variability of inter- and intraspecies density of cetaceans andprey within the area. Acoustic monitoring may be an effective means oftracking diurnal and annual activity of cetaceans in a long-term manner andcompare the activity to the presence and behavior of prey.

WEDNESDAY MORNING, 20 MAY 2009 BROADWAY I/II, 8:30 TO 11:15 A.M.

Session 3aAO

Acoustical Oceanography and Underwater Acoustics: Environmental Inferences in Inhomogeneous OceanEnvironments II

Mohsen Badiey, ChairCollege of Marine and Earth Sciences, Univ. of Delaware, Newark, DE 19716-3501

Chair’s Introduction—8:30

Contributed Papers

8:353aAO1. Information theory application to inversions of acoustic datafrom a continental shelf environment. David P. Knobles, Robert A. Koch,and Jason D. Sagers �Appl. Res. Labs., The Univ. of Texas at Austin, P.O.Box 8029, Austin, TX 78713�

This research examines the uncertainty in waveguide parameter valuesobtained from acoustic inversion of data collected in range-dependentenvironments. To account for range-dependence in the environmental pa-rameters, the number of inversion parameters must be increased. Generally,from a fixed data sample the uncertainty in the solution for individual pa-rameter values increases as the number of inversion parameters increases,especially if the structure of the propagated acoustic field is sensitive to theadditional parameters. This effect can be offset by prior information that re-duces the volume of the parameter search space and to a limited extent bylarger inversion data samples. How an inversion algorithm accounts forprior information is thus an essential issue to be addressed for range-dependent waveguides. Measurements made on the New Jersey shelf in70–90 m of water provide an opportunity to study the effects of environ-mental range dependence on sound propagation and inversion processing.Inversions based on pre-existing geophysical information are combined witha maximum entropy approach to quantify the amount of information on thewaveguide parameters that can be extracted from measured propagationover range-dependent tracks. Both towed sources emitting CW lines and im-pulsive sources are employed. �Work supported by ONR.�

8:503aAO2. Probability density functions of modal amplitudes and complexacoustic pressure in fluctuating shallow water waveguides. Kevin D.LePage �NATO Undersea Res. Ctr., Viale San Bartolomeo 400, 19126 LaSpezia, Italy�

The polynomial chaos method is applied to the problem of predicting theprobability density functions of complex modal amplitudes and acousticpressure in the presence of water column sound speed fluctuations in shal-low water waveguides. Results for both the intrusive implementation of thepolynomial chaos technique, where the governing coupled mode differentialequations for the complex modal amplitudes are augmented with the randomstates of the chaos expansion, and the non-intrusive method, where legacycodes can be run over an ensemble of ocean realizations and the results fit-ted by a truncated chaos expansion, are shown. Both methods give goodagreement with Monte Carlo histograms of the modal amplitudes and thepressure field for slight water column variability, but the non-intrusive for-

mulation shows more robustness for larger variability. The relative merits ofPC expansions for the complex modal amplitudes vs the log amplitudes forthe complex pressure amplitudes are also discussed.

9:053aAO3. Resolving spatial seabed variability by Bayesian inference ofseabed reflection inversions. Jan Dettmer, Stan E. Dosso �School of Earthand Ocean Scinces, Univ. of Victoria, Victoria, BC V8W 3P6, Canada�, andCharles W. Holland �The Penn State Univ., State College, PA�

This paper considers Bayesian inversion of seabed reflection-coefficientdata for multilayer geoacoustic models at several sites with the goal ofstudying spatial variability of the seabed. Rigorous uncertainty estimation isof key importance to resolve spatial variability between measurement sitesfrom the inherent inversion uncertainties. Geoacoustic uncertainty estima-tion is carried out including Bayesian model selection and comprehensiveestimation of data error statistics. Model selection is addressed using theBayesian information criterion to ensure parsimony of the parametrizations.Data error statistics are quantified by estimating full covariance matricesfrom data residuals, and a posteriori statistical validation is carried out. AMetropolis-Hastings sampling algorithm is used to compute posterior prob-ability densities. Five experimental sites are considered along a track locatedon the Malta Plateau, Mediterranean Sea, and the inversion results are com-pared to cores and subbottom profiler sections. Differences between sitesthat exceed the estimated geoacoustic uncertainties are interpreted as spatialvariability of the seabed.

9:203aAO4. A simplified model of frequency distortion in ocean acousticsignals by multiple interactions with a moving ocean surface and its usein oceanographic inversions. Stephen D. Lynch and Gerald L. D’Spain�Marine Physical Lab., Scripps Inst. of Oceanogr., 9500 Gilman Dr. 0701,La Jolla, CA 92093-0701�

Received omnidirectional spectra of low frequency narrowband tonesmeasured in a shallow ocean waveguide exhibit Doppler-shifted sidebandsat frequencies whose offsets are integer multiples of the dominant surfacewave frequencies. These observations suggest that higher order scattering isimportant. However, higher-order perturbation theory involving only asingle surface interaction does not predict the observed relative sidebandlevels. In particular, the higher order sidebands were often observed to in-crease in relative level to the main spectral peak during smaller surfacewave, and, therefore, smaller kh, conditions. A simplified model is presentedthat simulates the surface wave-induced frequency distortions as path-lengthmodulation caused by the vertical motions of the surface. The model incor-


porates multiple interactions with the moving surface, and quantitativelypredicts the effects on the received spectra of the spatial coherence of thesurface waves along the propagation path. The model results are identical tothose from higher order perturbation with a single interaction. The simpli-fied nature of this model allows it to be readily used to invert for variousproperties of the ocean surface wave directional spectrum. �Work supportedby ONR, Code 321�US�.�

9:353aAO5. Particle filter source tracking in a changing geoacousticenvironment. Caglar Yardim, Peter Gerstoft, and William S. Hodgkiss,�Marine Phys. Lab., 2038 Scripps Inst. of Oceanogr., Univ. of California,San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0238, [email protected]�

This paper addresses the problem of tracking the acoustic source param-eters such as the depth, range, and speed in evolving geoacousticenvironments. It is well known that inaccurate knowledge about the envi-ronmental parameters such as the sound speed profile �SSP�, water depth,sediment, and bottom parameters may result in significant errors in sourceparameters. To counter this, a particle filtering �PF� approach is adopted herewhere the geoacoustic parameters are tracked together with the source loca-tion and speed in a range-dependent environment. This allows accurate, real-time updating of the environment the ship is moving in and hence sourcecan be located at any time accurately. As a sequential Monte Carlo techniquethat can operate on nonlinear systems with non-Gaussian probability densi-ties, the PF is an ideal tracking algorithm to perform tracking of source andenvironmental parameters and their evolving probability distributions. Thealgorithm is tested on a sloping environment with the SSP, water depth, andsediment parameters evolving as the ship moves. The change in the waterdepth created the well-known “source mirage effect,” but the PF was stillable to track the true source, geoacoustic parameters, and their evolving den-sities in this spatially varying environment. �Work supported by ONR.�

9:503aAO6. Statistics of mode amplitudes in shallow water environments:Effects of random linear internal waves and nonlinear internal wavepackets. John Colosi �Naval Postgrad. School, 833 Dyer Rd., Monterey, CA93943, [email protected]�, Andrey Morozov, and Tim Duda �Woods HoleOceanograph. Inst., Woods Hole, MA 02543�

In shallow water environments there is presently an incomplete under-standing of the relative acoustical importance of the random linear internal-wave field compared to nonlinear internal waves packets. Using the randomcoupled mode theory of �Creamer �1996��, the nonlinear internal wave modecoupling theory of �Colosi �2007��, and Monte Carlo numerical simulationwe are able to demonstrate the important propagation physics when the twointernal wave fields act alone, and simultaneously. Importantly, we find thatfor acoustic frequencies less than roughly 500 Hz and for propagationranges of order 10s of kms mode propagation though the random internalwave field is very nearly adiabatic, and that cross mode coherences decayrapidly within the first 10 km. A surprising consequence of the decay ofcross mode coherence is that the mean intensity will be to first order insen-sitive to nonlinear internal wave packets if they are located past the de-coherence range. It will also be shown that uncorrelated modes have impor-tant implications for the approach to saturation. The adiabatic nature ofmode propagation though the random internal wave field may have impor-tant implications for shallow water acoustic remote sensing.

10:05—10:30 Break

10:303aAO7. Inversion for range-dependent water column sound speedprofiles in shallow water. Megan S. Ballard �Graduate Program in Acoust.,Penn State, P.O. Box 30, State College, PA 16804-0030, [email protected]�and Kyle M. Becker �Penn State, State College, PA 16804-0030�

Spatial and temporal variability of the sound speed field in the water col-umn can have a significant impact on acoustic propagation. It is difficult orsometimes impractical to measure fine scale variations in water columnproperties over an acoustic propagation path. When measurements are notavailable, water column properties must be approximated. In past work, in-verse methods based on acoustic tomography and matched-field processinghave been used to estimate mean water column sound speed profiles. Thedrawback of these methods is their inability to capture fluctuations in thewater column sound speed profile. In this work, a perturbative scheme usingmodal wave numbers is used to obtain range-dependent features of the watercolumn. Based on the work of Rajan et al. �1987�, a technique has beendeveloped to estimate water column sound speed profiles using historicaldata to constrain the inversion. This constraint allows for a robust inversion;the result is accurate both when the inputs are noisy and when the bottom ispoorly known. The new technique is demonstrated using data from the Shal-low Water 2006 �SW06� experiment. Inversion results are compared to insitu measurements from the towed CTD chain. �Work supported by NDSEGand ONR.�

10:453aAO8. The estimation of geoacoustic parameters via low frequencies(50–75 Hertz) for simulated shallow water test scenarios. A. Tolstoy�ATolstoy Sci., 1538 Hampton Hill Circle, McLean, VA 22101�

This work will demonstrate the success of using only a variety of lowfrequencies �50–75 Hz� for geoacoustic inversion in simulated SW06environments. The environments include a variety of scenarios �a thin, me-dium, or thick sediment layer over a half-space�, broadband sources at ap-proximately 1 km range �rge�, and a vertical array consisting of 16 phoneswhose depths are approximately known, i.e., we assume that array elementlocalization was available so that we can estimate phone depths �zphi� towithin about 1 m. The source depths �zsou� and water depths �D� are ap-proximately determined via time domain crossings seen at the array �see A.Tolstoy, J. Acoust. Soc. Am. 123, 3106 �2008��. Additionally, the oceansound-speed c�z� is assumed to be range-independent and approximatelyknown, e.g., via measurements or archival data. The use of only the 50–75Hz portion of the signal results in a need for less than perfect accuracy forzphi and c�z� while still giving excellent accuracy for estimated bottomparameters. Geometric parameters �such as rge, zsou, D, zphi� and c�z�would be more accurately determined by means of higher frequencies butthis would require much more CPU time. Uniqueness of the final “solution”is achieved for all but the thin sediment scenario.

11:003aAO9. Detection and classification of typhoons using underwateracoustic sensors in the western Pacific Ocean. Barry Ma �Dept. of ECE,Portland State Univ., 1900 SW 4th Ave., Portland, OR 97201,[email protected]� and Y. J. Yang �Naval Acad., Tsoying, Kaohsiung,Taiwan�

About two years of underwater ambient noise were collected using Pas-sive Aquatic Listeners �PALs� in the western Pacific Ocean. PALs were de-ployed using the bottom-mount or surface-mount buoys on the possible ty-phoon paths. Several episodes of intensive typhoon noise were recordedduring the passage of these powerful tropical storms. These acoustic data arecompared with other ancillary data for the classification of typhoons. Usingthe underwater ambient noise to classify the intensity of typhoons is a rela-tively reliable method. The instrument is placed away from the air-sea in-terface in a less destructible environment and provides relative in situ mea-surement of the wind speed. The ambient noise recordings from thedeployment also include the biology, shipping, and other surface noises, butthe noises from the typhoons are the most distinguishable against all othersources of noise. The noise budgets from different deployment sites are alsopresented.


WEDNESDAY MORNING, 20 MAY 2009 PAVILION EAST, 8:00 TO 11:45 A.M.

Session 3aBB

Biomedical Ultrasound/Bioresponse to Vibration and Physical Acoustics: Shock Wave Therapy I

Michael R. Bailey, CochairApplied Physics Lab., Univ. of Washington, Seattle, WA 98105

Thomas J. Matula, CochairApplied Physics Lab., Univ. of Washington, Seattle, WA 98105-6698

Invited Paper

8:00

3aBB1. Investigation of an ultrasound imaging technique to target kidney stones in lithotripsy. Anup Shah �Dept. of Urology,Univ. of Washington School of Medicine, 1959 NE Pacific St., Box 356510, Seattle, WA 98195, [email protected]�, MarlaPaun, John Kucewicz �Univ. of Washington, Seattle, WA 98105�, Oleg A. Sapozhnikov �Moscow State Univ., Moscow 119992, Russia�,Manjiri Dighe �Univ. of Washington School of Medicine, Seattle, WA 98195�, Hunter A. McKay �The Polyclinic, Seattle, WA 98122�,Mathew D. Sorensen �Univ. of Washington School of Medicine, Seattle, WA 98195�, and Michael R. Bailey �Univ. of Washington,Seattle, WA 98105�

Localization of kidney stones and targeting for lithotripsy can be challenges especially with ultrasound. However, twinkling artifacthas been observed where Doppler ultrasound imagers assign color to the stone. We report a preliminary investigation from our obser-vations in a porcine model and hypothesize why this artifact occurs. Glass beads, cement stones, and human stones were surgicallyplaced into the renal collecting system through the ureter. The stones were imaged using several transducers and ultrasound imagers. Inall cases, the twinkling artifact of the stone was observed, and its appearance and radiofrequency signature were unique from those ofblood flow. Calcium oxalate monohydrate stones and smooth stones were not more difficult to image, contrary to previous reports.Increasing gain or placing the focal depth distal to the stone enhanced the artifact, but other user controls showed little effect. Twinklingstarted at the lateral edges of the stone and spread over the stone as gain was increased. The evidence supports the hypothesis that smallmotions induced by radiation force or elastic waves in the stone cause changes in received backscatter, particularly at imaging anglesoblique to the stone surface. �Work supported by NIH DK43881 and NSBRI SMST01601.�

Contributed Paper

8:153aBB2. Shock wave lithotripsy treatment at 60 shock waves per minuteis an appropriate protocol to minimize tissue injury. Bret Connors,Andrew Evan, Philip Blomgren, Rajash Handa, Cynthia Johnson, JamesMcAteer �Dept. of Anatomy, IU School of Medicine, Ms-5055, 635 BarnhillDr., Indianapolis, IN 46202�, Lynn Willis �IU School of Medicine, India-napolis, IN 46202�, and James Lingeman �Int. Kid. Stone Inst., Indianapolis,IN 46202�

Previous work has shown that the size of the renal hemorrhagic lesioncaused by extracorporeal shock wave lithotripsy �SWL� is greatly reducedwhen shock waves �SWs� are delivered at 30 SWs/min instead of at themore commonly used rate of 120 SWs/min �0.08�0.02% versus 3.93

�1.29% of functional renal volume, P�0.006�. However, slowing the SWrate to 30 SWs/min greatly increases treatment time. Consequently, we in-vestigated whether an intermediate rate of 60 SWs/min also reduces lesionsize compared to treatment at 120 SWs/min. Methods: one kidney in 12 ju-venile pigs was treated at 120 SWs/min �n�7� or at 60 SWs/min �n�5� withan unmodified Dornier HM-3 lithotripter �2000 SWs, 24 kV�. After lithot-ripsy, the treated kidneys were fixed and removed to determine lesion size.Results: SWL at 60 SWs/min significantly reduced the size of the morpho-logical lesion compared to 120 SWs/min �0.42�0.23% versus 3.93�1.29%,P�0.034�. This reduction in lesion size was comparable to the lesion pro-duced at 30 SWs/min. Conclusions: SWL applied at 60 SWs/min producessignificantly less renal injury than SWL at 120 SWs/min, and produces anequivalent level of injury as that seen at 30 SWs/min.

Invited Papers

8:30

3aBB3. Renal heme oxygenase-1 upregulation after shock wave lithotripsy. Daniel L. Clark, Bret A. Connors, Andy P. Evan, RajashK. Handa, and Cynthia D. Johnson �Dept. of Anatomy Cell Biology, Indiana Univ. Sch. of Medicine, 635 Barnhill Dr., Indianapolis, IN46202, [email protected]�

Shock wave lithotripsy �SWL� is known to induce oxidative stress and a rapid inflammatory response in renal tissue. The purposeof this study was to determine the location and quantify markers for oxidative stress and inflammation in a porcine model of acuteSWL-induced renal injury. The lower pole calyx of left kidneys of female pigs received 2000 shock waves at 24 kV/2 Hz from a DornierHM3 lithotripter and subsequently monitored for 4 h. Heme oxygenase-1 protein �HO-1� was measured in renal microsomes by Westernblot. Renal medulla HO-1/-actin ratios were 1.186 � 0.48 for treated pole �F2�, 0.293 � 0.23 for treated kidney upper pole, and 0.122� 0.075 for contralateral kidney �n�6�. Thus, we observed an eightfold induction of HO-1 in renal medulla at F2 compared to the upperpole medulla of the treated kidney and the contralateral kidney medulla. In contrast, renal cortex at F2 did not show a similar HO-1induction. The highly localized HO-1 induction in SWL-treated renal medulla parallels our previously reported finding of interleukin-6.These data together suggest that an early inflammatory response and oxidative stress appear primarily in the treated renal medulla within4 h after SWL. �Work supported by NIH�.


8:45

3aBB4. Low-energy shock wave pretreatment results in greater vasoconstriction and less injury in the kidney compared tohigh-energy shock wave lithotripsy treatment alone. Rajash K. Handa, Andrew P. Evan, Bret A. Connors �Dept. of Anatomy and CellBiology, Indiana Univ. Sch. Med., Indianapolis, IN 46202�, Lynn R. Willis, Sujuan Gao �Indiana Univ. Sch. Med., Indianapolis, IN46202�, Marla Paun, and Michael R. Bailey �Univ. of Washington, Seattle, WA 98115�

Pretreating the kidney with low-energy shock waves �SWs� before administering a clinical dose of high-energy SWs has been foundto greatly decrease the hemorrhagic lesion that normally results from high-energy shock wave lithotripsy �SWL� treatment alone. Wetested the hypothesis that this novel pretreatment SWL protocol results in a greater and/or earlier renal vasoconstriction than clinicalSWL alone, which could potentially explain the reduced bleeding in the kidney. Anesthetized pigs were treated with a clinical dose ofSWs �2000 SWs, 24 kV, 120 SWs/min� or the pretreatment protocol �500 SWs, 12 kV, 120 SWs/min 3-min pause 2000 SWs, 24kV, 120 SWs/min� using the HM3 lithotripter. Sonography �color and pulsed ultrasound� was used to locate a resistance artery withinthe SW-treated pole of the kidney and to take resistance index �RI� measurements from the blood vessel to estimate the resistance/impedance to blood flow. The results demonstrated that RI increased �renal vasoconstriction� earlier and greater during the pretreatmentprotocol compared to normal clinical SWL. Constricted blood vessels would likely be less prone to rupture by SWs and, if broken,would bleed less—resulting in a smaller hemorrhagic lesion.

Contributed Paper

9:003aBB5. Efficiency of spark discharge in electrohydraulic lithotripsy. YuriA. Pishchalnikov, Mark M. Kaehr, R. Jason VonDerHaar, Irina V.Pishchalnikova, and James A. McAteer �Dept. of Anatomy and Cell Biol-ogy, Indiana Univ. Sch. of Medicine, 635 Barnhill Dr., Indianapolis, IN46202, [email protected]�

Electrohydraulic lithotripters and SWT devices generate shock waves bydischarge of a high-voltage capacitor through submerged electrodes. As theelectrodes age, the interelectrode gap widens. How this affects the efficiencyof spark generation was studied using a research HM3-clone lithotripter.Widening of the interelectrode gap ��0.3 mm with new electrodes; �2.5mm after 4000 discharges� increased the lag-time to breakdown ��0 to �30µs, respectively�. Increased lag-time as electrodes aged was associated with

partial discharge of the capacitor �leakage promoted by �0.6 mS conduc-tivity of the surrounding water�, such that the average energy remaining atthe capacitor at the moment of breakdown was reduced four times comparedto new electrodes. However, with new electrodes almost 90% of the energywas lost in the circuitry rather than in the spark, as the resistance of thespark �R�0.03 �� was much smaller than the resistance of the remainder ofthe circuit—including the high-voltage switch and connective wires �r�0.23��. With old electrodes, most of the energy was released in the spark, as theelectric efficiency R/�Rr� approached �90%. The product of electric effi-ciency and capacitor energy agreed closely with both the acoustic energyand the volume of the primary bubble produced at spark discharge. �Worksupported by NIH-DK43881.�

Invited Paper

9:15

3aBB6. Bubble dynamics with tissue confinement in shock-wave lithotripsy. Jonathan B. Freund �Mech. Sci. Eng., Univ. of Illinoisat Urbana–Champaign, 1260 W Green St., MC-244, Urbana, IL 61801, [email protected]� and Ratnesh Shukla �Univ. of Illinois atUrbana–Champaign, Urbana, IL 61801�

Estimates are made of the effect of confinement by tissues on the action of small bubbles when subjected to strong pressure waves.The applications of interest are biomedical procedures involving short strong ultrasound bursts or weak shocks of the kind delivered inshock-wave lithotripsy. Confinement is anticipated to be important in suppressing mechanical injury and slowing the rate of its spread.We consider bubbles in a liquid such as blood within a small vessel in the tissue. A generalization of the Rayleigh–Plesset equationallows us to estimate the effect of the elasticity and viscosity of the surrounding tissue. Ranges of soft-tissue properties are estimatedfrom a variety of different measurements available in literature. Solutions suggest that elasticity is insufficient to significantly alterbubble dynamics, but that viscosities from the mid-to-high range of those suggested might play a significant role in suppressing bubbleaction. Simulations in two space dimensions of a shocked bubble in a waterlike fluid interacting with a viscous material show that themuch more complicated bubble jetting dynamics in this configuration is also significantly suppressed. The dynamics of this suppressionis investigated.

Contributed Paper

9:303aBB7. Simulation of three–dimensional crack profiles in shock wavelithotripsy. Maddegedara Lalith Lakshman Wijerathne, Hide Sakaguchi�JAMSTEC, Yokohama Inst. for Earth Sci., 3173-25 Showa-machi, Yoko-hama 236-0001, Japan.�, Kenji Oguni, and Muneo Hori �Univ. of Tokyo,Bunkyo-Ku, Tokyo 113-0032, Japan.�

Some of the experiments reported by Xufeng Xi and Pei Zhong in 2001were simulated to explore the sources of crack initiation and propagation inshock wave lithotripsy �SWL�. An interesting result they reported was theT-shaped crack pattern in plaster of paris cylinders, subjected to transversepressure pulses. This nontrivial crack pattern and some others were simu-lated, in 3-D, using a numerical technique called PDS-FEM. According to

this 3-D simulations, it was found that the interference of reflected and fo-cused high pressure pulse, by the distal surface, and the lagging low tensilephase created high tensile regions in the cylindrical sample. These highstress regions initiate and drive two horizontal and vertical cracks leading tothe T-shaped crack. Due to the lack of data, a typical lithotripter pressurewave profile and material properties for plaster of paris were used. The ob-served crack patterns were successfully regenerated in 3-D, irrespective ofthese approximations. The distances between the vertical crack and the dis-tal face for the crack patterns of the experiments and numerical simulationsare nearly 0.34�d and 0.35�d, respectively �d�diameter�. This quantitativecomparison shows the potential applications of PDS-FEM for exploring andfurther development of SWL technology.


Invited Papers

9:45

3aBB8. Shock wave interaction with cavitation bubble clusters generated in lithotripsy. Derek C. Thomas, Todd A. Hay, and MarkF. Hamilton �Appl. Res. Labs., The Univ. of Texas at Austin, Austin, TX 78713-8029�

Collapse of cavitation bubbles generated in shock wave lithotripsy is essential to the comminution of kidney stones. After passageof the shock, however, if insufficient time has elapsed for the bubbles to dissolve, acoustic scattering from residual bubbles shields thestone from the next shock. Therefore, cavitation also limits the maximum firing rate. As important as collective bubble dynamics are tothe efficacy of shock wave lithotripsy, behavior of the bubble clusters is among the least understood physical processes involved. Amodel was developed previously for the pulsation and translation of dynamically coupled spherical gas bubbles �Ilinskii et al., J. Acoust.Soc. Am. 121, 786 �2007��. This model was augmented to account for interaction with the focused shock wave incident on the clusterat the order of the Born approximation. Diffraction of the shock wave is described by the KZK equation. The model predicts translationand coalescence of the bubbles due to transmission of the shock through the cluster. Predicted also is the acoustic wave scattered fromthe cluster, which in the forward direction is the leading order effect of the cluster on the transmitted shock wave. �Work supported bythe ARL McKinney Fellowship in Acoustics and NIH DK070618.�

10:00—10:15 Break

10:15

3aBB9. Shock wave lithotripsy can alter urinary acid-base pH regulation. Rajash K. Handa, Bret A. Connors, Cynthia D. Johnson,Andrew P. Evan �Dept. of Anatomy and Cell Biology, Indiana Univ. Sch. Med., Indianapolis, IN 46202�, Mahesh C. Goel, James E.Lingeman �Methodist Hospital Inst. for Kidney Stone Disease, Indianapolis, IN 46202�, Elaine M. Worcester, and Fredric L. Coe �Univ.of Chicago, Chicago, IL 60637�

The renal papilla is particularly susceptible to injury by shock waves �SWs�. Since the papilla is vital for urinary pH regulation, wehypothesized that shock wave lithotripsy �SWL�-induced damage of papillae will alter the pH of the urine. Experiments were conductedin four female adult Gottingen minipigs. The HM3 lithotripter delivered a total of 8000 SWs �24 kV, 120 SWs/min� among all papillaeof one kidney, while the untreated, opposite kidney was used as control. The pigs were allowed to recover and 5 weeks later they wereanesthetized. Serial urine collections were obtained from the SW-treated and untreated kidney. Urine was collected under mineral oiland immediately tested for its pH. Both kidneys were then perfusion fixed for histological analysis. Urinary pH was 0.17 units greater�P�0.05� in the SW-treated kidney compared to the untreated kidney. Histology showed scarring in all regions of the SW-treated kid-ney, with thick ascending limbs and collecting ducts having grossly abnormal morphologies indicative of cellular proliferation. Theseresults suggest that SWL-induced injury can cause remodeling of nephron structures and long-term impairment in the regulation ofurinary pH.

10:30

3aBB10. Ureteroscopic ultrasound technology to size kidney stone fragments: Proof of principal using a miniaturized probe ina porcine model. Mathew D. Sorensen, Anup Shah �Dept. of Urology, Univ. of Washington Sch. of Medicine, 1959 NE Pacific St., Box356510, Seattle, WA 98195, [email protected]�, Michael S. Canney �Univ. of Washington, Seattle, WA 98105�, Oleg A. Sa-pozhnikov �Moscow State Univ., Moscow 119992, Russia�, Joel M. H. Teichman �Univ. of British Columbia, Vancouver, BC V6Z 1Y6,Canada�, and Michael R. Bailey �Univ. of Washington, Seattle, WA 98105�

Background: the ability to measure stone fragment size could help prevent attempting to extract too large a stone fragment. Weevaluated the ability of a 1.2 mm �3.6 French� ultrasound probe to measure stone fragments in a porcine kidney. Methods: 15 humanstones of three types �five each calcium oxalate, cystine, calcium phosphate� sized 3–7 mm were placed deep in a porcine kidneycollecting system. The sound speed of each stone type was determined using a separate reference stone. A 2 MHz, 1.2 mm needlehydrophone was used to send and receive ultrasound pulses. Stone thickness was calculated as d�c*t/2 by determining the signal transittime through the stone, t, and the stone sound speed, c. Calculated stone thicknesses were compared to digital caliper measurements.Results: Stone size was determined for all 15 stones. Correlation between ultrasound-determined thickness and caliper measurementswas excellent �r2�0.90, p�0.0001� with ultrasound performing well in all three stone types. All stone measurements were accuratewithin 1 mm, and ten �66%� stone measurements were accurate within 0.5 mm. Conclusions: Ultrasound-based measurements are ac-curate and precise using a 3.6 French probe with stone fragments placed deep in a porcine kidney. �Work supported by Grants NIHDK43881 and NSBRI SMST01601.�

Contributed Papers

10:453aBB11. Ellipsoidal-reflector high intensity focused ultrasound systemwith integrated safety monitoring. Joshua Samuels and Vesna Zderic�Dept. of Elec. and Comp. Eng., The George Washington Univ., 801 22ndSt. NW, Washington, DC 20052, [email protected]�

High intensity focused ultrasound �HIFU� transducers can be created us-ing concave piezo elements, acoustic lenses, phased arrays, or ellipsoidalreflectors. By using a 2 MHz cylindrical piezoelectric crystal and a brassellipsoidal reflector, it was possible to use the base of the transducer tohouse specific devices which can be integrated into a safety system for thedevice. This system assists in focal point positioning, ablation confirmation,

as well as assuring proper flow of coolant through the attached water pillowto couple the device. These methods combine to protect the patient and thedevice itself from improper use or dangerous positioning of the focal pointwithin the tissue. The proposed system utilizes an unfocused 3.5 MHz ul-trasound transducer to act as a rangefinder, determining the distance of thetissue from the transducer. A simple graphical user interface allows themaximum allowed depth of ablation to be user defined and a warning dis-played if needed. A water pillow with integrated flow meter is used to pro-vide cooling and coupling to the tissue. There is also a housed video camerain the device which could provide visual confirmation of ablation if usedlaparoscopically or for superficial lesions.


11:003aBB12. In vivo simulation of shock wave lithotripsy: Wave focusing ininhomogeneous materials. Jeffrey Krimmel and Tim Colonius �Caltech1200 E California Blvd., MC 104-44, Pasadena, CA 91125, [email protected]�

Shock wave generation and focusing in electrohydraulic, electromag-netic, and piezoelectric lithotripters are simulated numerically. Inhomogene-ities associated with wave propagation in vivo are modeled using data fromThe Visible Human Project. The approximate time-domain relaxation modelof Yang and Cleveland �2005� was used to simulate attenuation and disper-sion in the tissuelike media. The simulations utilize a MUSCL-type shockcapturing scheme with adaptive mesh refinement �AMR�. In vitro focal re-gion pressure measurements compare favorably with available experimentaldata for each lithotripter type. Preliminary in vivo simulation results showsignificant dispersion associated with the nonuniform sound speed, includ-ing increases of up to 50% in focal pressure amplitudes and the presence ofmultiple pressure minima/maxima in the focal waveform. We will also dis-cuss the extension of the AMR framework to account for cavitation via apreviously developed ensemble-averaged continuous two-phase flow model.

11:153aBB13. Kidney stone tracking in vitro using an acoustic triangulationparadigm. Jonathan M. Kracht and Robin O. Cleveland �Dept. of Mech.Eng., Boston Univ., 110 Cummington St., Boston, MA 02215�

During shock wave lithotripsy, stones undergo motion which can placethem outside the focal zone of the lithotripter. This results in shock wavesbeing delivered that do not impact the stone but may injure tissue. Trackingstones using diagnostic ultrasound imaging ��4 MHz� has proven to bechallenging. Here we employed an array of seven relatively low-frequency��600 kHz� elements to detect scattered signals from an artificial kidneystone in the presence of a tissue phantom. Using an optimization routine, the

time of flight to each element and array geometry were used to determinethe most likely location of the stone. A comparison of threshold crossing andcross-correlation for detecting signal arrival indicated that while the formeryielded faster computation time, the latter was more robust to noise. Stoneposition was determined to within 2 mm for locations within 10 mm of thefocus. For distances beyond 10 mm, the optimization routine was not able toreliably predict stone location but could indicate that the stone was notwithin the focal region. �Work supported in part by NIH.�

11:303aBB14. Lung hemorrhage produced by exposure to underwateracoustic impulses. Diane Dalecki, Sally Z. Child, and Carol H. Raeman�Dept. of Biomedical Eng., and the Rochester Ctr. for Biomedical Ultra-sound, 310 Goergen Hall, Univ. of Rochester, Rochester, NY 14627, [email protected]�

Underwater acoustic impulse sources are used in various commercialand military applications. The objective of this study was to investigate theresponse of mammalian lung to exposure to underwater acoustic impulses. Alaboratory-based acoustic exposure system was developed to investigate thebioeffects of underwater impulses. Underwater acoustic impulses were gen-erated using a ten cubic inch air gun operated in a large water tank. Under-water acoustic impulses with peak pressure amplitudes ranging from 0�sham� to 110 kPa were investigated. Experiments were performed withanesthetized adult mice. Each exposure consisted of five acoustic impulseswith approximately 20 s between impulses. Mammalian lung hemorrhagecan occur in response to exposure to underwater acoustic impulses. Thepressure threshold for lung hemorrhage resulting from five air gun impulseswas approximately 50 kPa. The extent of lung damage increased with in-creasing pressure amplitude. The results of this work are relevant to estab-lishing safety guidelines for swimmers and divers exposed to underwatersound fields.

WEDNESDAY MORNING, 20 MAY 2009 COUNCIL SUITE, 9:00 TO 11:15 A.M.

Session 3aEA

Engineering Acoustics, Structural Acoustics and Vibration, Noise, and Acoustical Oceanography: AcousticalEngineering of Wind Turbines

Thomas R. Howarth, ChairNaval Sea Systems Command Division Newport, Newport, RI 02841


Invited Papers

9:05

3aEA1. Wind turbines: Why they are noisy and what to do about it. Frits van den Berg �GGD, P.O. Box 2200, 1000CE Amsterdam,The Netherlands, [email protected]�

Sound from modern, tall wind turbines is related to sleep disturbance and is, per decibel, more annoying than sound from commonsources such as road or air traffic. Surveys among residents indicate that there are several reasons for this: the swishing character of thesound, the intrusiveness at night, and the visibility of the wind turbine�s�. Residential reaction is also determined by the attitude towardswind turbines in the landscape and by economical benefits. From acoustical research different explanations have arisen as to why thesound is amplitude modulated. For a distant observer it is the result of the change in trailing sound level due to the change in wind thatthe revolving blades encounter. High night-time sound levels are due to an increase in rotor height wind speed simultaneously with adecrease in near-ground wind speed. Wind turbine design has been directed to higher yields per turbine. Less attention has been givento low noise blades and rotor speed reduction. Low noise design could also include a reduction in the modulation amplitude and moresophisticated speed reduction; viz., at high annoyance conditions. Also, involving residents in wind farm planning may have a highpotential to reduce annoyance.


9:30

3aEA2. An overview of the acoustical activities at the National Wind Technology Center. Arlinda Huskey �NREL, NWTC, 1617Cole Blvd., MS 3911, Golden, CO 80401, Arlinda�[email protected]�, Moriarty Patrick, Jeroen van Dam �NREL, NWTC, Golden, CO80401�, Eric Simley, and Scott Palo �Univ. of Colorado�

The National Wind Technology Center �NWTC� has been involved in wind turbine acoustics since the 1980s. The areas of workinclude standards development, measurement and analysis, prediction code development, and acoustic arrays. Most measurements areconducted to the IEC 61400-11, a standard specifically for acoustic measurements of wind turbines. The NWTC is involved in thedevelopment of this standard. The standard results in reports of overall levels as well as tonality. The NWTC has also developed asemiempirical acoustic noise prediction code for wind turbines. Validation of this code with test data �both wind tunnel and fieldmeasurements� shows reasonable prediction accuracy for both airfoil self noise and turbulent inflow noise. Lastly, to assist with windturbine noise reduction and to identify the loudest components an acoustic array was developed to better locate noise on wind turbines.This paper will describe the NWTC’s past and current activities in wind turbine acoustics including test methods and results.

9:55

3aEA3. Ocean acoustic noise budgets: Application to the environmental assessment of offshore wind power generation. James H.Miller, Gopu R. Potty, Andres Nunez Perez �Dept. of Ocean Eng., Univ. of Rhode Island, Narragansett, RI 02882, [email protected]�,Kathleen Vigness Raposa �Marine Acoust., Inc., Middletown, RI 02842�, and Jeffrey A. Nystuen �Univ. of Washington, Seattle, WA98105-6698�

A noise budget is a listing of the various sources of acoustic noise and their associated ranking by importance. A number of differenttypes of budgets can be conceived using various acoustic measures such as intensity, energy, or duration of maximum amplitude level.These budgets are typically parameterized by frequency and are usually computed over 1/3 octave bands. As part of the environmentalassessment of the proposed offshore wind power generation project under the Rhode Island Special Area Management Plan �SAMP�,noise measurements were made using the Passive Acoustic Listener �PAL� systems off the coast of Rhode Island prior to the installationof any wind power facilities. Two PALs were deployed within two miles of Block Island in water depths of 20 m from October 6 toNovember 11, 2008. The data included noise spectra and source identification every 3 min. Short snapshots of unusual sounds were alsorecorded. From this data, the ocean acoustic noise budget is computed with contributions from shipping, wind/waves, marine mammals,and rain from 500 Hz to 50 kHz. The ship noise data is correlated with ship traffic data from the Automatic Identification System �AIS�.�Funding provided by the Rhode Island Office of Energy Resources.�

10:20

3aEA4. Prediction methodologies for tonal and broadband noise from horizontal-axis wind turbines. Brent Paul, RudolphMartinez, Donald Thompson, and James Uhlman �CAA-Alion Corp., 84 Sherman St., Cambridge, MA 02140 [email protected]�

This paper describes a set of computational-analytic predictive tools for the following mechanisms of aerodynamic sound and vi-bration for a wind turbine’s blades in ducted or open arrangements: �a� Infrasound and tonal low-frequency nearfield noise from theinteraction of blades with a nonuniform meanflow that is steady in its own reference frame; �b� mid-frequency broadband noise from the“haystacked” chopping of an incident turbulent freestream; �c� high-frequency noise from self-generated turbulence near the trailingedge of each blade’s suction side. Contributors to tonal mechanism �a� include the rotor’s static loads as required by power generation�nearfield “Gutin” component of infrasound�, and operation in a local wind shear or in the mean wake of the turbine’s tower when setup as a downstream machine. These predictive tools include models of the spatially nonuniform mean and turbulent flows that typicallystrike a wind turbine’s blades, as well as preprocessors of that information when made available by either field measurements or off-linecalculations. The codes’ physical content includes the possibility of uneven spacing for the turbine’s blades and for their interaction withstatistically inhomogeneous turbulence for mechanism �b�. Sample predictions compare the codes’ estimates of sound production tomeasurements from the open literature.

Contributed Papers

10:453aEA5. Methodologies to address limitations of the ISO9613-2 standardfor wind turbine noise propagation modeling. Erik J. Kalapinski �TetraTech EC Inc., 133 Federal St., Boston, MA 02110, [email protected]�

The accuracy of the noise propagation modeling results is dependent on:�1� the sound source data entered into the model as reported by wind turbineequipment manufacturers as specified under per IEC 64100-11 standard; �2�site specific topographical, meteorological, and terrain conditions; and �3�the propagation algorithms of the acoustic modeling standard that areapplied. For wind energy facilities sited in the US, the ISO 9613-2 standardis most commonly used due to its proven effectiveness to accurately predictthe sound levels at a distance for industrial and commercial projects in anoutdoor environment. The propagation algorithms employed by the ISO9613-2 standard account for geometrical divergence, atmospheric absorp-tion, ground attenuation, screening effects, and favorable sound propagationconditions that would occur during omnidirectional downwind meteorologi-cal conditions. The purpose of this paper is to identify limitations inherent inthe ISO 9613-2 standard to the specialized application of wind turbineacoustics and nonstandard atmospheric conditions. Methodologies are pre-

sented to more accurately describe atmospheric and lateral attenuation ef-fects, which can result in significant uncertainties in the noise levels calcu-lated both in proximity and at distant receptor locations.

11:003aEA6. Vibration analysis of turbine low-pressure bladed-disk in500-MW fossil power plant. Dooyoung Lee, Youngchae Bae, Heesoo Kim,Yookryun Lee, Hongil Choi, and Hyun Lee �Hydro & Fossil Power Genera-tion Lab., KEPRI, 103-16 Munji Yusung Daejon, Korea, 305-380, [email protected]�

Many failures of turbine blades are caused by the coupling of aerody-namic forcing with bladed-disk vibration characteristics. Vibration analysisfor an individual turbine blade does not include all the coupled characteris-tics of whole bladed-disk system. This paper shows the coupled vibrationcharacteristics of a low-pressure �LP� turbine bladed-disk in a 500-MW fos-sil power plant for the purpose of confirming equipment integrity. In order toverify the finite element model, analytic and experimental modal analysesfor a single blade were performed and reviewed with boundary conditionsnot only where both ends were free to move but also where its root was


fixed. Natural frequencies and corresponding mode shapes were calculatedfor the bladed-disk first, and then proximity of modes to sources of excita-tion was assessed by means of interference diagrams to examine resonance.The result of analysis was ascertained by being compared with a field testfor the bladed-disk without centrifugal and aerodynamic forces. In addition,

dynamic stress as well as steady stress which results from centrifugal andsteady-state steam forces was also calculated at dangerous modes ofoperation. It is expected that these dynamic characteristics will be used ef-fectively to identify the root causes of blade failures and to perform promptmaintenance.

WEDNESDAY MORNING, 20 MAY 2009 STUDIO SUITE, 8:25 TO 11:45 A.M.

Session 3aED

Education in Acoustics and ASA Student Council: Project Listen Up

James M. Sabatier, ChairNational Ctr. for Physical Acoustics, Univ. of Mississippi, University, MS 38677


Invited Papers

8:30

3aED1. A simple experiment for understanding resonant air columns. Theodore F. Argo, IV, Chad A. Greene, and Preston S. Wilson�Mech. Eng. Dept. and Appl. Res. Labs., The Univ. of Texas at Austin, Austin, TX 78712-0292, [email protected]�

One goal of Project Listen Up is to enhance children’s understanding of acoustics through engagement in basic acousticsexperiments. This work proposes an experiment that examines the resonant frequencies of an air column. Equipment for this experimentconsists of a small tunable oscillator circuit connected to a loudspeaker, which can also be used for other experiments in the kit. Theexperimenter will provide a cardboard tube, rubber band, plastic wrap, and sand. Resonance is demonstrated by placing the loudspeakerat the base of the tube, covering the top of the tube with a plastic wrap membrane, and placing sand grains on top of the membrane. Asfrequency is adjusted, the sand grains are excited at the resonance frequencies of the tube. Frequencies at which sand motion is observedcan be compared to a simple algebraic model, which relates the length of the tube to the resonance frequencies of the system. Anoptional advanced experimental track investigates the effect of varying the length of the tube. This experiment develops intuition for therelationship between frequency and wavelength and builds understanding of resonant systems.

8:45

3aED2. Sound speed measurements in air using a variable sound source and tubes. Stanley A. Cheyne and Walter C. McDermott�Dept. of Phys. and Astronomy, Hampden-Sydney Coll., Hampden-Sydney, VA 23943�

Sound speed measurement using standing waves and tubes is a standard experiment in every introductory physics laboratory. It isan experiment that is relatively simple to understand both conceptually and mathematically. The idea behind this work is to reproducethe same experiment, at low cost, making it suitable for project listen up. Two approaches were made. The first was to design andconstruct a small, low cost, variable sound source that could be used to determine the resonances of several fixed length tubes. Thedevice is simple in design and easy to use. As the frequency is varied, the resonances can be determined by listening with the ear. Oncedone, the sound speed can be easily calculated. The second method was to use a free, online, function generator as the sound source andrepeat the experiment as previously discussed. Results of both methods will be given and demonstrated along with pros and cons ofeach.

9:00

3aED3. Why we have two ears—a hands-on experiment comparing monaural and binaural hearing. Ralph T. Muehleisen �Civil,Environ., and Architectural Eng., Illinois Inst. of Technol., 3201 S. Dearborn St., Rm. 228, Chicago, IL 60616�

Whether they fly, swim, crawl, or walk, vertebrates have binaural auditory systems. Two ears provide redundancy in case of injuryto the auditory system, improve the ability to detect quiet sounds and, perhaps most importantly, improve the ability to localize sound.This paper describes a simple experiment in which two individuals work together to investigate the sound localizing abilities of a humanusing monaural and binaural hearing. In the experiment, one person sits blindfolded in the center of a circle and acts as a listener. Theother person moves a sound source around a circle, equidistant from the listener while the listener attempts to locate the direction of thesource. The experiment is repeated for both monaural �with an earplug in one ear� and binaural �using both ears� hearing and forimpulsive and low frequency tonal sources. The experiment is best attempted in an environment with very few nearby reflecting sourcessuch as the outdoors or a very large room.


9:15

3aED4. Two-dimensional normal modes: Experiment and finite element analysis. Uwe J. Hansen �Dept. of Chem. & Phys., IndianaState Univ., Terre Haute, IN 47809�

Bending wave propagation on a two-dimensional plate is reduced to standing waves with the imposition of boundary conditions.These standing wave patterns can be observed with sand, which accumulates near the nodal lines. These sand patterns are usually calledChladni patterns after Chladni, who first observed and described them. Using a simple lapel microphone, these mode patterns can alsobe illustrated by noting the phase shift when observing the near-field sound pattern very close to the vibrating plate. Both Chladnipatterns and phase mapping of patterns will be illustrated. A relatively inexpensive software package enables finite element calculationsof vibrating plates. Normal mode vibration can easily be illustrated in animation on a computer screen. Both the calculation process andthe animation will be illustrated.

9:30

3aED5. Acoustics outreach and scouting: A merit badge proposal. Kent L. Gee, Brian E. Anderson, Tracianne B. Neilsen, and ScottD. Sommerfeldt �Dept. of Phys. and Astron., Brigham Young Univ., N283 Eyring Sci. Ctr., Provo, UT 84602, [email protected]�

The success of the Girl Scouts of America �GSA� and the Optical Society of America’s “Project Lighten Up” and the proposed“Project Listen Up” have prompted a discussion of how Scouting can be used as an outreach vehicle to interest today’s youth in scienceand, more particularly, in acoustics. One possibility for this would be the drafting of a “Sound and Audio” merit badge for the BoyScouts of America �BSA� or a similar activity award for the GSA. The BSA currently offers 121 merit badges for scouts, includingvaried topics such as archeology, rifle shooting, plumbing, truck transportation, and coin collecting. Although there are physical science-related merit badges �e.g., composite materials, chemistry, nuclear science�, there is not a badge that deals directly with acoustics. Thistalk will outline how an acoustics-related merit badge may help engage youth interest in science and discuss ideas for possible badgerequirements.

9:45

3aED6. Wave interaction effects for all ages. Scott D. Sommerfeldt �Dept. of Phys., Brigham Young Univ., N181 ESC, Provo, UT84602, [email protected]�

Wave interaction effects occur in many everyday situations. A number of important principles associated with these interactions canbe readily demonstrated without the need for extensive and expensive equipment. Using two low-cost speakers, it is possible to easilydemonstrate the basic principle underlying active noise control by placing the speakers close together and first wiring the speakers“in-phase” to achieve constructive wave interference and then wiring the speakers “out-of-phase” to achieve destructive waveinterference. This setup results in a global attenuation of the sound field, making the audible effect easily discernible. The dependenceof the interaction on frequency and spacing �kd� can be demonstrated by changing the frequency of the excitation signal. In addition, byseparating the speakers the interaction of two waves to create a standing wave can be demonstrated, and the nodes/antinodes establishedcan be audibly heard as the listener moves his/her ear through the field. Finally, these concepts can be used to understand why loud-speakers are mounted in enclosures. As the loudspeaker is placed in an enclosure the direct interaction of �out-of-phase� waves from thefront and back of the loudspeaker cone is inhibited, thus resulting in increased radiation efficiency.

Contributed Papers

10:003aED7. A simple analytical demonstration of transient and steady-stateresponse in a dissipative closed waveguide based on the d’Alembertsolution. Jerry H. Ginsberg �G. W. Woodruff School of Mech. Eng., GeorgiaInst. of Technol., Atlanta, GA 30332-0405, [email protected]�

Previously �J. H. Ginsberg, J. Acoust. Soc. Am. 119, 1954–1960 �2006��,the d’Alembert solution of the wave equation was adapted to address the

response to initial conditions of a one-dimensional waveguide whose termi-

nations have an arbitrary real �possibly dissipative� impedance. The tech-

nique creates virtual images on the other �i.e., nonphysical� side of each wall

to convert the closed waveguide to one of infinite extent. The present work

extends the development to cases where an arbitrary velocity is applied to

one wall. The imaging technique allows one to visually track the evolution

of the spatial pressure profile and the relation of temporal waveforms at

various locations. The relatively low level of mathematical skills entailed in

the formulation makes the method accessible to students at all levels. Ap-

plication of the technique to periodic excitation of the boundary leads to vi-

sual representation of various effects, including reverberation time and vari-ous resonance effects, such as uncontrolled growth in the absence of

dissipation and approach to steady-state when dissipation is present. Sound

files generated from the synthesized connect the physical and audible

phenomena.

10:15—10:30 Break

10:303aED8. Hands on and homemade coupled oscillators for Project ListenUp. Sean M. Mock and Murray S. Korman �Dept. of Phys., U.S. NavalAcad., Annapolis, MD 21402, [email protected]�

A coupled pendulum oscillator experiment recently developed within theU.S. Naval Academy Physics Department seems a possible candidate for theProject Listen Up initiative. A plexiglass frame supported by four legs sus-pends two 500 g masses 30 cm below by two chains of paper clips each,meeting in the shape of a V on either bob. A light spring �k�3.64 N/m� con-nects the two, completing the coupled oscillator system. Displacement of theoscillators was measured using Pasco motion sensors, a Vernier LabPro unit,and a laptop. LOGGERPRO and MATHEMATICA software helped compare theorywith experiment. However, one does not need these resources to experimentwith coupled oscillators—it can be improvised using ordinary householdmaterials for young students! An inexpensive wooden picture frame with is-let screws supports pendulums using two Dixie cups filled with sand orcoins as masses. The possibilities for learning seem endless! A simple stop-watch, meter stick, fulcrum, and measuring cups are incorporated in experi-mental and theoretical comparisons, including the periods of normal modes.Students can explore density through balancing masses with volumes ofwater. Demonstrating beat frequencies from mistuned xylophone bars orguitar strings conveys a subtlety of the experiment without overpoweringthe young minds of future scientists.


10:453aED9. Helmholtz resonator experiment for Project Listen Up. MarianneC. Sparklin and Murray S. Korman �Dept. of Phys., U.S. Naval Acad., An-napolis, MD 21402, [email protected]�

The behavior of sound waves and resonant effects can be observed usingHelmholtz resonators. Resonators are built from identical round woodenboxes purchased from a craft store. The tops are glued and drilled with holediameters from 2–3 cm. We can study the resonant behavior as a function ofhole diameter only. The end effect is large compared with the thickness ofthe orifice �0.6 cm�. In the experiment, a swept tone �100–900 Hz� from asmall speaker drove the resonator. One studied the output of the microphonelocated near the orifice. One could use a swept spectrum analyzer, a functiongenerator, or tuning fork with varying weights to measure the resonant fre-quency of the box. A plot of hole diameter versus frequency can be com-pared with the theoretical Helmholtz resonant frequency prediction, whichdepends on the volume of the box, the cross sectional area, the sound speedof air, and the effective length of the hole. One can model the effectivelength of the resonator as the thickness of the top plus a constant times thediameter of the hole and get good agreement with the established end cor-rection found in textbooks.

11:003aED10. The energy flow for a spherical acoustic lens: Ray and wavemethods vs experiment. Cleon E. Dean �Phys. Dept., P.O.B. 8031, GeorgiaSouthern Univ., Statesboro, GA 30460-8031, [email protected]�and James P. Braselton �Georgia Southern Univ., Statesboro, GA 30460-8093�

A simple classroom demonstration consists of a weather balloon filledwith carbon dioxide, a sound source, and a microphone. Since the speed ofsound is slower in carbon dioxide than in air at room temperature and pres-sure, the balloon acts as a positive spherical acoustic lens. The accuracy ofray methods in locating the acoustic focus versus a full-blown wave solutionapproach has been presented previously �Cleon E. Dean and James P. Bra-selton, “The energy flow for a spherical acoustic lens: ray vs. wave meth-ods,” J. Acoust. Soc. Am. 123, 3520 �2008�.� Theoretically, this problempresents particular difficulties if the sound source lies in the near fieldregion. The sound emitter is treated as a dipole source equivalent to a rigidoscillating sphere of small size and amplitude of motion relative to thescatterer. The energy flux around the balloon has been visualized by both ray

methods and by the acoustic energy flux vector field. The geometrical rayresults and the energy flux vector field resulting from the wave solution arecompared with experiment.

11:153aED11. The effect of the teaching-learning sequences connecting soundwave at microlevel and macrolevel on the student’s understandings forsound transmission. Hyungjun Kim �Phys. Education Dept., Seoul Natl.Univ, Daehak-dong, Gwanak-gu, Seoul 151-742, [email protected]�and Junehee Yoo

Previous studies reported that students had some difficulties in under-standing sound waves as longitudinal waves. In this research, most ofteaching-learning sequences described sound waves at macrolevel, whichwere supposed as one source of these difficulties. So teaching-learning se-quences connecting sound wave at microlevel and macrolevel were devel-oped and effects were investigated. These teaching-learning sequences werefocused on bridging between the movement of particles in air and move-ments of slinky springs and simulation using the EXCEL program. In additionto that, explaining wave phenomena at macrolevel by the movement of par-ticles at microlevel was emphasized. Predict-observe-explain strategy wasused. Evaluated worksheets and video-records were analyzed to figure outconceptual changes.

11:303aED12. Modal analysis for undergraduate laboratories and projects.Andrzej Kotlicki and Chris Waltham �Dept. of Phys. and Astronomy, Univ.of British Columbia, 6224 Agricultural Rd., Vancouver, BC V6T 1Z1,Canada�

Vibrational analysis of structures �musical instruments for example� re-quires a means of excitation, motion detection and a data acquisition system.None of these needs to be very expensive. We have constructed an impacthammer using a piezoelectric crystal from an old barbeque lighter; this pro-vides rapid excitation at all frequencies up to 1 or 2 kHz. Motion detectionis now possible using extremely light �less than 1 g� microelectromechnicalsystems �MEMS� accelerometers that cost only a few dollars each. Two-channel data acquisition at 44.1kHz per channel is available to anyone witha computer equipped with a soundcard. More flexible external systems arealso available in the $200 range. Thus, modal analysis is easily within thebudgets of undergraduate laboratories. In this presentation we will empha-size the calibration of the impact hammer and evaluation of the MEMSaccelerometers.


WEDNESDAY MORNING, 20 MAY 2009 EXECUTIVE SALON II/III, 8:00 TO 11:50 A.M.

Session 3aNS

Noise: Noise Litigation

John Erdreich, ChairOstergaard Acoustical Assoc., 200 Executive Dr., West Orange, NJ 07052


Invited Papers

8:05

3aNS1. Hearing loss litigation. Robert A. Dobie �Dept. of Otolaryngol., UC-Davis, Sacramento CA 95817�

Most hearing loss in American adults is attributable to aging, noise, or a combination of these two. While most claims for noise-induced hearing loss are handled administratively in workers compensation, litigation against employers, premises owners, and manu-facturers of noisy equipment continues to pose interesting challenges. Issues of negligence often involve professionals with expertise innoise control, hearing conservation program management, product labeling, and human factors. There are usually two primary issues forclinician experts: How severe is the hearing loss, and what caused it? Audiologists and otologists can draw upon a mass of research tosupport reasonable opinions in cases with complete data sets. Unfortunately, important data from the past �e.g., changes in noise ex-posure and hearing loss over a career� are often impossible to obtain. Forensic consulting is terra incognita for most clinicians, requiringanalyses and judgments that are rarely called for in clinical practice.

8:35

3aNS2. Minneapolis et al versus the Metropolitan Airports Commission. Paul Schomer �Schomer and Assoc., Inc., 2117 Robert Dr.,Champaign, IL 61821, [email protected]�

The city of Minneapolis has a law protecting the quietude in various land use areas, including residential areas. In this legal action,plaintiff asserted that the Metropolitan Airports Commission was adversely and significantly affecting the quietude of the residents inthe 60–65 DNL zone and that a 5-dB noise insulation package in homes in that zone would ameliorate the situation. There were fourtasks for plaintiff’s expert witnesses; �1� Define quietude; �2� Show that without the airport quietude existed in the 60–65 DNL zone;�3� Quantify the impacts including annoyance, speech interference, and sleep disturbance; and �4� Quantify the benefits of a 5-dB noiseinsulation package. The results were a negotiated settlement for $128 million.

9:05

3aNS3. Qualification of an aircraft ground run-up enclosure using a novel sound monitoring and analysis approach. Kerrie G.Standlee �Daly-Standlee & Assoc., Inc., 4900 SW Griffith Dr., Ste. 216, Beaverton, OR 97005�

This paper describes a sound monitoring and analysis program developed to determine if a ground run-up enclosure �GRE� installedat the Portland International Airport was effective in reducing aircraft engine run-up noise radiated to residential neighborhoods duringnighttime hours. A noise monitoring and analysis program was developed to fulfill conditions of approval imposed by the OregonDepartment of Environmental Quality �DEQ� prior to the construction of the facility. A novel approach was developed whereby unat-tended sound level meters were used to collect one-second Leq and hourly statistical noise level data near the GRE and at communitylocations of interest. This data, combined with GRE usage data and weather data, was then subjected to a multistep analysis procedure.The process was found to be very effective at determining when ground run-up events caused community noise levels exceeding DEQlimits. By the end of the project, the procedure was being used to assess 99 percent of the run-ups occurring within the GRE. The soundmonitoring and analysis procedure became a very reliable tool in demonstrating that the GRE complied with its conditions of approval.

9:35

3aNS4. Noise issues affecting litigation in condominiums. Jerry G. Lilly �JGL Acoust., Inc., 5266 NW Village Park Dr. Issaquah, WA98027�

Serving as an expert witness in legal actions involving residential condominiums is often a harrowing and extremely challengingtask, regardless of which side you represent. If you are representing the HOA, you have to educate your client so that they understandthat the mere ability to hear your neighbor is not necessarily unusual and may not be grounds for a defect. If you are representing thearchitect, developer, or contractor, you have to educate them as to the code requirements as well as the various acoustical performanceguidelines that will undoubtedly be introduced by the HOA. In either event, if you do not do your homework you are leaving yourselfexposed to be grilled by opposing counsel �in deposition or at trial� without mercy. This presentation will discuss the author’s experiencein dealing with these issues, with specific emphasis on problems with the testing standards and performance guidelines that exacerbatethe problem.


10:05—10:20 Break

10:20

3aNS5. Warning audibility in industrial accidents. John Erdreich �Ostergaard Acoust. Assoc., 200 Executive Dr., W. Orange, NJ07052�

Industrial accidents related to warning audibility may be adjudicated in the worker compensation environment or in state courts. Onefactor that may determine whether the incident becomes a compensation case or a tort is if the employer could reasonably expect thesituation to require an audible warning. The second factor to evaluate is the adequacy of the warning itself. Thus, it is the responsibilityof the acoustician to educate the trier of fact about not only the science of audition, but also the state of the art in that represents aconsensus of methods to provide such warnings. An example of such a case will be presented.

Contributed Papers

10:503aNS6. Can race car sound break windows? David Braslau �David Bra-slau Assoc., Inc., 1313 5th St. SE, Ste. 322, Minneapolis, MN 55414�

Sound from a special class of race cars was cited as cause for suddenbreakage of a large pane of tempered glass in a private box that fell andinjured a spectator below. Analysis of previously recorded race track noisefrom a similar track in Minnesota showed that sound levels could exceed theHubbard rattle criteria but no conclusions could be drawn regardingbreakage. Because of time constraints, sound level measurements from arace in Ohio of this vehicle class were taken by Campanella Associates forreference. Those measurements were compared with previously measuredlevels of other vehicle classes and found to be higher at some frequencies.Since a recorded demonstration performed by the plaintiff showed breakageof a similar pane of glass with an induced flaw and continuously appliedsound at 70 to 80 Hz, a field test on a similar window with simulated soundlevels based upon measurements from the special vehicle class race was per-formed with assistance from Synergistic Design Associates. A simulatedsound level as high as 117 dBA was generated at the window withoutbreakage. Some conclusions on potential glass breakage from incidentsound will be presented. �Work supported by Johnson & Lindberg, P.A.�

11:053aNS7. Deficiency of the Massachusetts Pure Tone Noise Regulation.Michael Bahtiarian �Noise Control Eng. Inc., 799 Middlesex Trnpk., Bil-lerica, MA 01821, [email protected]�

The Commonwealth of Massachusetts Department of EnvironmentalProtection �MADEP� noise regulation has two parts. The first part involvesoverall A-weighted noise and requires that no source of sound be greaterthan 10 dB above the background noise. A second part states that no puretones are allowed. A pure tone condition is defined by the MADEP as anyoctave band that is greater than the adjacent bands by 3 dB. The author wasinvolved in community noise investigation that showed the deficiency of thepure tone requirement. A suburban community complained of bothersomenoise from an industrial abutter. Noise measurements were taken by otherconsultants which did not register as a pure tone. The author was hired bythe community group to conduct measurements on their behalf. Similar oc-tave band measurements were taken with similar results. However, measure-ments with finer one-third octave band showed significant tonal activity.When compared to commercial standards for pure tones the tonal criterionwas met. Further examination of narrowband data showed why the originaloctave band measurements were not registering pure tone conditions. Theauthor will present his suggestion for changes to the MADEP regulation andwelcomes input from others dealing with similar tonal requirements.

11:203aNS8. Uncertainty in field and laboratory acoustical testing: Achallenge for the acoustical industry. John LoVerde and Wayland Dong�Veneklasen Assoc., 1711 16th St, Santa Monica, CA 90404, [email protected]�

The statistical uncertainty in acoustical testing has been insufficientlystudied in the acoustical community. There are a limited number of studiesquantifying measurement uncertainties, especially in the field, but evenwhere uncertainties have been documented, they are largely ignored inpractice. As was documented in a previous case �LoVerde and Dong, J.Acoust. Soc. Am. 124, 2441 �2008��, it is common practice to assume thatthe test results have low uncertainties �even if published uncertainties arelarge� and that variations in the results are due to variations in materials,errors in construction, etc. This can be particularly important in noise liti-gation, where acoustical ratings that are lower than expected are often au-tomatically assumed to be due to construction defect, even though they maybe within the expected range. Even without errors in construction, the un-certainties in the acoustical test procedure may be such that some assemblieswill meet the relevant statutory requirements and other, nominally identicalassemblies will fail. Recent experience and insight will be presented regard-ing the definition of a construction defect in acoustical assemblies, the over-lap of responsibilities between contractors and designers, and the interpre-tation of building code requirements.

11:353aNS9. Designing petrochemical plants to permit retrofitting of anyadditional controls needed to meet community noise limits. Frank H.Brittain �Bechtel Corp., 2255 Peavine Valley Rd., Reno, NV 89523�

Designing petrochemical, power, or industrial plants to meet communitynoise limits can be expensive. To meet stringent limits, incremental costsoften exceed one million dollars per decibel. There is considerable uncer-tainty, including: overly conservative or unrepresentative vendor noise data,limitations of ray-tracing software, questionable accuracy beyond 1000 m,lack of TL and absorption data below 125 Hz, unreliable IL data for pipelagging at all frequencies, unexpected operating conditions, and vendors notmeeting their equipment noise limits. Atmospheric effects can cause varia-tions of A-weighted community noise levels of 25 dB at 100 m from a re-finery, which can make meeting a not-to-exceed noise limit difficult andrisky. Further, lack of experience with noise control of any participant �noisecontrol engineer, project, owner, regulators, or vendors� can substantially in-crease uncertainty. Including sufficient noise controls to cover these uncer-tainties will be expensive, often overly conservative, and often unnecessarilyexpensive. One way to substantially lower costs and risks is designing theplant to permit delaying some but not all controls until start-up—if needed.This paper describes the planning needed to permit a partial reliance on ret-rofit controls, what type of controls can be delayed until start-up, and spaceallocation. Examples are included.


WEDNESDAY MORNING, 20 MAY 2009 BROADWAY III/IV, 8:30 TO 11:15 A.M.

Session 3aPA

Physical Acoustics: Infrasound and Outdoor Sound Propagation

D. Keith Wilson, ChairU.S. Army Cold Regions Research Lab., Engineering Research and Development Ctr., Hanover, NH 03755-1290

Contributed Papers

8:303aPA1. On tropospheric ducting in infrasound. Roger Waxler and PhilipBlom �NCPA, Univ. of Mississippi, University, MS 38677, [email protected]�

Infrasound can propagate to ranges of many hundreds of km. Signals re-ceived on the ground at ranges of 200 km or more have propagated high intothe atmosphere through the stratosphere and thermosphere. At shorterranges, the propagation is dominated by structure in the lower atmospheresuch as the jet stream and the atmospheric boundary layer. Theoretical re-sults on the influence of the lower atmosphere on infrasound propagationwill be presented.

8:453aPA2. On the fast arrivals seen in impulse propagation in the nocturnalboundary layer. Philip Blom and Roger Waxler �Natl. Ctr. for PhysicalAcoust., Univ. of Mississippi, University, MS 38677�

On clear dry nights over flat land, an acoustic duct forms in the atmo-spheric boundary layer. The duct is formed by a temperature inversion in thelowest few hundred m of the atmosphere and by the stiff wind, known as thenocturnal jet, which commonly develops above the temperature inversion.An impulsive signal undergoes strong dispersion as it propagates in the noc-turnal duct and is received at long ranges from the source as an extendedwave train consisting of a series of distinct arrivals followed finally by a lowfrequency tail. The first arrival is of interest here. Through its interactionwith the nocturnal jet, the first arrival is often anomalously fast. Accompa-nying the increased propagation speed is a marked decrease in amplitude. Itwill be shown that an explanation for this behavior is given by geometricalacoustics.

9:003aPA3. Impulsive sound propagation in coastal regions. Xiao Di, CarrickTalmadge, Roger Waxler, Kenneth E. Gilbert �Natl. Ctr. for Phys. Acoust.,Univ. of Mississippi, University, MS 38677�, and David A. Conner �U.S.Army Aviation and Missile Command�

Influenced by the coastal temperature profile and wind profile, the re-sulting sound speed profiles in coastal regions have certain unique features,such as double inversion zones. As a result, long range sound propagationpresents certain properties due to these features. An impulsive sound propa-gation experiment had been conducted in the morning hours of the summerof 2007 in the coastal Florida area. The test field was 7 km long. Three pro-pane cannons were used during the experiment, located at each end of thetest field and in the middle of the test field. Both upwind and downwindpropagation data were collected and will be presented. The data showed thatcoastal region meteorology has a dominant effect on long range soundpropagation. Simulated sound propagation results using measured meteoro-logical data are compared with measured impulsive sound propagation data.

9:153aPA4. Investigation of dominant sources of pressure fluctuations andinfrasonic wind noise in microphones. John Paul Abbott, Richard Raspet,Jeremy Webster, and Jiao Yu �Natl. Ctr. for Physical Acoust., Dept. of Phys.and Astronomy, Univ. of Mississippi, University, MS 38677�

Investigation of the time dependent relationship between the verticalwind velocity fluctuations and the pressure sensed on the ground as mea-sured in an open field is done to determine if the turbulence-shear term ofthe Poisson equation is the dominant source of pressure fluctuations and in-frasonic wind noise present in microphones, or some other source. The windvelocity was measured using a three-axis ultrasonic anemometer and sixone-dimensional ultrasonic anemometers. The pressure was measured simul-taneously using two half-inch free-field pressure microphones, one placedflush with the ground, the other at a height of 1 m above the first. The an-emometers were also situated above and adjacent to the microphones. Thethree axis anemometer was set at a height of 1 m, and the six, one-dimensional anemometers, as a vertical array from a height of 0.1–2 mabove the ground. As this is still an ongoing investigation, only a descriptionof the experiment and the current findings are presented and discussed.

9:303aPA5. New models for wind noise measured in a flat surface underturbulent flow. Jiao Yu, Richard Raspet, Jeremy Webster, and JohnPaulAbbott �Natl. Ctr. for Physical Acoust. and Dept. of Phys. and Astron., Univ.of Mississippi, University, MS 38677, [email protected]�

We have previously developed models for predicting the power spectraldensity of the wind noise pressure measured in a flat plate outdoors from themeasured power spectral density of the turbulence and the measured windvelocity profile above the plate �Yu et al., Proceedings of NCAD 2008,NoiseCon2008-ASME NCAD�. Recently we have corrected an error in themodel for the logarithmic profile wind velocity gradient results and have de-veloped an improved integration method. Also, we have developed a pre-diction for arbitrary wind velocity profiles using the previous single expo-nential model. Typical results comparing our predictions with ourmeasurements are presented and analyzed. A simple algebraic fit to the pre-diction for the logarithmic profile fit form is also provided for use by others.�Research supported by the U.S. Army TACOM-ARDEC at Picatinny Arse-nal, NJ.�

9:453aPA6. Calculations of wind noise underneath a foam covering at theground surface. Jiao Yu, Richard Raspet, Jeremy Webster, and JohnPaulAbbott �Natl. Ctr. for Physical Acoust. and Dept. of Phys. and Astron., Univ.of Mississippi, University, MS 38677, [email protected]�

A foam windscreen reduces the wind noise generated at a microphone.Similarly, a thin foam covering above a surface mounted microphone alsolowers the wind noise level effectively. Recent research has focused on de-veloping a physical model for calculating the wind noise pressure fluctua-tion spectrum measured by a foam covered microphone under a turbulentflow based on our current model for flush mounted bare microphones. Thefoam surface not only reduces the wind noise at the microphone, but alsoprevents direct exposure of the microphone to the flow, which reduces themeasurement’s sensitivity to details of the meteorological conditions. In thistalk, the calculation model will be introduced, and the comparisons betweenour predictions with the model and our measurements down to low wavenumber will be presented and discussed. �Research supported by the U.S.Army TACOM-ARDEC at Picatinny Arsenal, NJ.�


10:00—10:15 Break

10:153aPA7. Study of the impact of input uncertainties on acousticpropagation. Bruce Ikelheimer, Micah Downing, and Michael James �BlueRidge Res. and Consultants, 13 1/2 W. Walnut St., Asheville, NC 28801�

A modular system of acoustical tools has been developed that integratesthe physical factors controlling the propagation of acoustical signals. Firstand foremost, this system provides a prediction of the noise from a source toa receiver location. This ray-tracing prediction takes into account the localterrain, changes in ground impedance, turbulence, and thermal and windgradients. This propagation prediction is combined with a noise source thatcan handle fully three-dimensional, spectral source descriptions. The modeluses a six-dimensional definition of the source location and orientation toselect the radiation angle from the source to the receiver. Levels of audibilityof the received signal are then calculated based on the received noise levels,the local ambient noise levels, and the expected listener acuity. Each input tothe model has uncertainties with the potential to generate errors that cascadethrough the system. Differing atmospheric, terrain, and ground impedanceconditions have been tested in our model both individually and in combina-tions to see how they interact. The goal is to have an understanding of theconfidence level of audibility provided a known level of uncertainty on theinput data.

10:303aPA8. Acoustic temperature measurement in a full-scale rocket noisefield. Jarom H. Giraud, Kent L. Gee, John E. Ellsworth, and Derek C.Thomas �Dept. of Phys. and Astronomy, Brigham Young Univ., N283 ESCProvo, UT 84602�

Acoustic pressure measurements in high-amplitude sound fields arecommon, but acoustic temperature measurements are relatively rare. This isprimarily because thermometers exhibit thermal lag and, consequently, alimited frequency range. In this study, a 1 µ diam platinum wire resistancethermometer was used to measure temperature fluctuations generated bypropagating noise produced by a horizontally fired, static GEM-60 solidrocket motor. The data are compared with those calculated from the pressuredata of a nearby 3.18 mm condenser microphone by assuming an ideal adia-batic process.

10:453aPA9. Rise times of low-energy, free-space propagating acousticshocks. Thomas B. Gabrielson, Timothy M. Marston �Graduate Program inAcoust., Penn State Univ., PO Box 30, State College, PA 16804�, and MarkS. Wochner �The Univ. of Texas at Austin, Austin, TX 78713-8029�

Characteristics of the “ideal” shock, a one-dimensional step change inpressure, are reasonably well established; however, the freely propagatingshock with finite duration is challenging to model and measure. These chal-lenges are reflected in an extensive body of literature over several decades.In this paper we present a method for producing free-space propagatingshocks, measurements of rise time with minimal contamination by turbu-lence, and model results that account for spreading, absorption �includingmolecular relaxation�, and nonlinearity. The shocks are produced using anacoustic pipe filter to condition the irregular pressure release of either bal-loon pops or starter-pistol shots. The shocks range in peak pressure from 10to 1000 Pa and in rise time from 10 to 0.5 µs. Rise-time measurements aremade using a custom piezoelectric polymer wideband microphone with ameasurement range that overlaps with that of a diffraction-corrected 1/8-inch measurement microphone. The exponential-decay time constant beyondthe pressure peak is typically less than 100 µs, which may be too rapid topermit development of characteristics associated with relaxationmechanisms: rise times over the entire range measured here are well pre-dicted by accounting for classical and rotational absorption only.

11:003aPA10. Three-dimensional numerical simulation of sonic boomdiffraction around buildings using a dispersion-relation-preservingscheme. Sang I. Cho and Victor W. Sparrow �Grad. Program in Acoust., ThePenn State Univ., 201 Appl. Sci. Bldg., Univ. Park, PA 16802�

A finite difference time domain approach is used to model the tempo-rally and spatially dependent pressure loading on a rigid structure due to anincident low-amplitude N-wave sonic boom. Analytically, one expectsstrong diffraction due to building corners and pressure doubling near rigidwalls. The three-dimensional linear wave equation is sufficient to model theinteraction between the structure and the low-amplitude sonic boom at theground level. Applying a fourth-order dispersion-relation-preserving schemeand a four-level explicit time marching scheme, an excellent dispersioncharacteristic is achieved without sacrificing computational efficiency of thealgorithm. NASA flight testing at Edwards, CA during the summer of 2006is numerically simulated by matching the geometries of the simulated struc-ture to the actual residential house used for the flight test and using thewaveform of a recorded boom as the incoming wave for the simulation. Adirect comparison to the experimental data allows the quantitative validationof the simulation results. The feasibility of using this model for calculationof the pressure loads on other structures can be determined based on theaccuracy of this numerical solution. �Work supported by NASA. The authorsappreciate NASA making the 2006 and 2007 flight data available for thiswork.�


WEDNESDAY MORNING, 20 MAY 2009 GALLERIA SOUTH, 8:45 A.M. TO 12:00 NOON

Session 3aPP

Psychological and Physiological Acoustics: Impacts of Hearing Impairment

Peggy B. Nelson, ChairDept. of Speech, Language and Hearing Science, Univ. of Minnesota, Minneapolis, MN 55455

Contributed Papers

8:453aPP1. A personal perspective on unilateral hearing loss. Brian D.Dushaw �Appl. Phys. Lab., Univ. of Washington, 1013 N.E. 40th St., Se-attle, WA 98105, [email protected]�

Although I have been unilaterally deaf since birth, only later in life haveI realized the extent of this handicap and how I can best manage it. Theeffects of this hearing loss are complicated, being an interplay of physics,psychology, social interaction, etc. Because people are able to adapt, the ex-tent of this “unseen” handicap is underappreciated. Responses by the publicto an informative website �http://909ers.apl.washington.edu/�dushaw/SSD�suggest that this handicap has a universal nature. Obvious effects are theinabilities to locate sound or to bilaterally process sound signals. Less ob-vious effects are a heightened sensitivity to noise: as masking to a desiredsignal, as a fatigue factor, as an impediment to mental concentration. Thedifficulties encountered when talking over the telephone to someone who isspeaking in a noisy environment may give one an appreciation of the effects.Even less obvious effects are the long-term social implications of thehandicap: the tendency to ignore those on one’s deaf side, the inability tofunction “normally” at noisy events such as parties, ASA receptions, etc., ora tendency to irritability in noisy environments. In this unscientific talk, Iwill attempt to highlight issues that may be deserving of additional study.

9:003aPP2. Masking period patterns of exponentially ramped and dampednoises in hearing-impaired listeners. Jennifer Lentz and Yi Shen �Dept. ofSpeech and Hearing Sci., Indiana Univ., Bloomington, IN�

Noises that are modulated with either an exponentially rising �ramped�,repeating modulator or a falling �damped�, repeating modulator may evokestrong perceptual differences. To explore a possible cochlear contribution tothese perceptual differences, masking period patterns �MPPs� of ramped anddamped noises were measured for normal-hearing listeners at differentstimulus levels and for hearing-impaired listeners. By time-reversing theramped MPP, comparisons can be made between thresholds for which themasker power was the same between ramped and damped noises. Previousresults showed that for normal-hearing listeners, the MPP of a ramped noiseis considerably shallower than the MPP of a damped noise. The present re-sults indicated that the differences between the damped and the time-reversed ramped MPPs were the largest at moderate stimulus levels and thesmallest at low and high stimulus levels. Listeners with hearing loss exhib-ited no difference in the damped versus time-reversed ramped MPPs. Re-sults will be discussed in terms of contributions of the cochlear nonlinearityand central auditory processes.

9:153aPP3. Modulation detection interference in listeners with cochlearhearing loss: Effect of modulation depth and onset delay. Jungmee Leeand Soonha Yook �Dept. of Speech, Lang. and Hearing Sci., Univ. of Ari-zona, 1131 E. 2nd St., Tucson, AZ 85721�

Modulation detection interference �MDI� was measured for listenerswith normal hearing �NH� and cochlear hearing loss �HI�. The signal was 1kHz, and the interferer was 2 kHz. The stimuli level was 50 or 22 dB SL.The interferer was modulated with 8 Hz at various modulation depths �25,50, 75, or 100%�. The onset of signal was delayed by 0, 125, 250, 375, 500or 625 ms relative to onset of the interferer. For NH subjects, MDI increased

systematically with increasing modulation depth of the interferer. MDI al-most disappeared with 375 or 500 ms onset delay except a condition withthe interferer of 25% modulation depth where there was no MDI at allacross different onset delay conditions. In contrast, for HI subjects, therewas quite an amount of MDI even with the interferer of 25% modulationdepth, and MDI was greater than NH for all modulation depths at 0 and 125ms onset delays, suggesting that the perceived modulation depth of the in-terferer might be exaggerated for HI than for NH.

9:303aPP4. Frequency modulation detection, frequency selectivity, andspeech recognition in noise by hearing-impaired listeners. Van Summers,Matthew Makashay, Joshua Bernstein �Army Audiol. & Speech Ctr., WalterReed Army Medical Ctr., 6900 Georgia Ave., NW, Washington, DC 20307�,Sarah Melamed, and Marjorie Leek �VA Medical Ctr., Portland, OR 97201�

Reduced ability to make use of temporal fine structure �TFS� informa-tion may contribute to deficits among hearing impaired �HI� listeners forspeech recognition in competing background sounds. The broad tuning typi-cally observed in HI listeners will produce more complex patterns of TFS asinput to the auditory nerve, and these patterns may be more difficult to en-code and/or interpret by higher auditory centers. In the current study, wetested HI listeners on a frequency-modulation �FM� detection task thoughtto require the use of TFS cues, on tone detection in notched-noise to assessfrequency selectivity, and on speech recognition in continuous and modu-lated background sounds. Performance on the psychoacoustic tasks wastested at four frequencies �500, 1000, 2000, and 4000 Hz� at levels between60 and 85 dB SPL �approximating the range of third-octave band levels inthe speech stimuli�. HI listeners with similar audiometric thresholds showedclear differences in frequency tuning, FM detection thresholds, and speechperformance. Relationships between the psychoacoustic measures in thefour frequency regions and between these measures and speech performancewill be discussed.

9:453aPP5. Relative contributions of spectral and temporal cues for speechrecognition in patients with sensorineural hearing loss. Li Xu, NingZhou, Katherine Rife, and Rebecca Brashears �School of Hearing, Speechand Lang. Sci., Ohio Univ., Athens, OH 45701�

The present study was designed to examine speech recognition in pa-tients with sensorineural hearing loss �SNHL� when both temporal and spec-tral information in the speech signals were co-varied. Four subjects withSNHL were recruited to participate in consonant and vowel recognition teststhat used speech stimuli processed through a noise-excited vocoder. Thenumber of channels was varied between 2 and 32, which defined spectralinformation. The lowpass cutoff frequency of the temporal envelope extrac-tor was varied from 1 to 512 Hz, which defined temporal information. Re-sults indicate tremendously individual differences among the subjects withSNHL. For consonant recognition, patterns of relative contributions of spec-tral and temporal information were similar to those in normal-hearingsubjects. The utility of temporal envelope information appeared to be nor-mal in the hearing-impaired listeners. For vowel recognition, the perfor-mance plateau was achieved with numbers of channels as high as 16–24,much higher than expected, given that the frequency selectivity in patientswith SNHL might be compromised. In order to understand how hearing-


impaired listeners utilize spectral and temporal cues for speech recognition,future studies will be necessary to elucidate the relationship between fre-quency selectivity as well as central processing capability and speech rec-ognition performance using vocoded signals.

10:00—10:30 Break

10:303aPP6. Discrimination of formant-like glides in gated noise: Effect ofsensation level. Peggy Nelson, Yingjiu Nie �Dept. of Speech-Lang.-HearingSci., Univ. of Minnesota, 164 Pillsbury Dr. SE, Minneapolis, MN 55455,[email protected]�, Magdalena Wojtczak, and Gordon Stecklein �Univ.of Minnesota, Minneapolis, MN 55455�

Listeners with sensorineural hearing loss �SNHL� do not experiencemasking release for speech in fluctuating noise, as normal-hearing listenersdo. One hypothesis suggests dip listening may be difficult because fre-quency glides, or speech formant transitions, may be difficult to discriminateat low sensation levels when in the presence of fluctuating noise. Normal-hearing listeners were tested for their ability to discriminate 100-ms fre-quency glides with center frequencies of 800 and 2500 Hz. They were testedin quiet and in the presence of 500-ms of 8-Hz square-wave gated broad-band noise at a signal-to-noise ratio of �10 dB. Listeners were tested at low�10–15 dB SL� and moderate �30–40 dB SL� signal levels. Preliminary re-sults suggest that glide discrimination thresholds �measured as % change�are similar for low- and moderate-level stimuli in quiet; glide thresholds arepoorer in gated noise than in quiet; and glide thresholds are poorest whenlow-level stimuli were presented in gated noise. These results suggest thatwhen formants or glides are presented at low levels and in gated noise, dis-crimination abilities may be reduced. Implications for understanding mask-ing release for speech by listeners with hearing loss will be discussed. �Worksupported by NIH 5R01DC008306.�

10:453aPP7. Comodulation masking release and speech perception:Implications for dip-listening by cochlear implant patients. Antje Ihlefeld�MRC Cognition and Brain Sci. Unit, 15 Chaucer Rd, Cambridge CB2 7EF,England, [email protected]�, Barbara G. Shinn-Cunningham �BostonUniv., Boston, MA 02215�, and Robert P. Carlyon �MRC Cognition andBrain Sci. Unit, Cambridge CB2 7EF, England�

Compared to normal-hearing �NH� listeners, cochlear implant �CI� lis-teners struggle to identify speech when a source of noise interferes and dopoorly when trying to listen in the dips of a modulated masker. In NH lis-teners, masker energy outside the spectral region of a target tone can im-prove target detection, a phenomenon referred to as comodulation maskingrelease �CMR�. Here we examined whether a comodulated flanking noiseimproves speech identification in a modulated noise masker, both for NHlisteners identifying vocoded speech and for CI listeners. In experiment 1,NH listeners identified noise-vocoded speech �taken from a closed-setspeech corpus� in a background of speech-shaped noise with or without aflanking narrow band of noise outside the spectral region of the target. Themasker and flanker were either both 16-Hz square-wave modulated or wereunmodulated. Performance was better in modulated than in unmodulatednoise and, importantly, this difference was greatest when the comodulatedflanker was present, consistent with the idea that CMR can introduce seg-regation cues between target and masker that help to listen in the dips of themasker. Experiment 2 tested CI listeners with the same experimentalparadigm.

11:003aPP8. Masking release for speech in listeners with real and simulatedhearing impairment. Joseph G. Desloge, Charlotte M. Reed, Louis D.Braida, Zachary D. Perez, and Lorraine A. Delhorne �Res. Lab. ofElectron.s, Massachusetts Inst. of Technol., 77 Massachusetts Ave., Cam-bridge, MA 02139, [email protected]�

The current study examined the effects of audibility and age on the re-lease of masking for speech in interrupted versus steady-state noise in lis-teners with real and simulated hearing loss. The absolute thresholds of each

of ten hearing-impaired listeners were simulated in normal-hearing listenersthrough a combination of spectrally shaped masking noise and multibandexpansion for the octave bands with center frequencies from 0.25–8 kHz.Each individual hearing loss was simulated in two groups of three normal-hearing listeners �one age-matched group and one non-age-matched group�.The speech-to-noise ratio �S/B� for 50%-correct identification of HINT sen-tences was measured in backgrounds of steady-state noise and temporallymodulated �10-Hz square-wave� noise at two overall levels for unprocessedspeech and for speech that was amplified with the NAL-PR prescription. Re-sults indicate that the magnitude of the release from masking �the differencein S/B obtained in steady-state versus interrupted noise� observed in indi-vidual hearing-impaired listeners was generally well produced in bothgroups of simulated-loss listeners. Thus, release of masking appears to bedetermined primarily by audibility regardless of age. Predictions of maskingrelease derived from the Speech Intelligibility Index �SII; ANSI S3.5-1997�will be compared to the observed values. �Work supported by NIH-NIDCDR01 DC00117.�

11:153aPP9. Spectral modulation detection training in older adults withhearing loss. Andrew T. Sabin, Cynthia A. Clark �Dept. of Commun. Sci.and Disord., Northwestern Univ., 2240 Campus Dr. Evanston, IL 60201,[email protected]�, David A. Eddins �Univ. of Rochester, Roches-ter, NY 14618�, Sumitrajit Dhar, and Beverly A. Wright �NorthwesternUniv., Evanston, IL 60201�

Individuals with hearing loss are poorer than normal-hearing listeners atdetecting patterns of peaks and valleys of sound level spread across audiofrequency �spectral modulation detection�—an important skill for speechand music perception. In this preliminary report we examined whether lis-teners with hearing loss could improve on spectral modulation detectionwith practice. We trained older adults with sensorineural hearing loss �n�7��1 hr/day for 7 days to distinguish a 400–3200 Hz noiseband with a flat-spectrum from one with a 2 cyc/oct sinusoidal spectral modulation. Modu-lation depth was varied adaptively to determine the detection threshold.Their mean thresholds improved significantly from 18.9 to 12.8 dB. Theselisteners also improved at both a lower and a higher untrained spectralmodulation frequency �1 and 4 cyc/oct�, but showed no change on a measureof frequency selectivity. Interestingly, a separate group of younger normal-hearing adults who received the same training �n�7� did not improve on thetrained �6.9 to 6.6 dB� or untrained conditions. Normal-hearing listeners hadlower pre-training thresholds than individuals with hearing loss, and acrossall listeners the magnitude of individual improvement was correlated to pre-training threshold �r�0.92�. Listener age and/or hearing loss could havecontributed to these across-population differences.

11:303aPP10. Multidimensional perceptual scaling of musical timbre byhearing-impaired listeners. Kelly Fitz, Matt Burk, and Martin McKinney�Starkey Labs, 6700 Washington Ave., S., Eden Prairie, MN 55344,kelly�[email protected]�

We examine the impact of hearing loss and hearing aid processing on theperception of musical timbre. Our objective is to identify significant timbrecues for hearing-impaired listeners, and to assess the impact of hearing aidsignal processing on timbre perception. Hearing aids perform dynamic,level-dependent spectrum shaping that may influence listeners’ perception ofmusical instrument timbres and their ability to discriminate among them.Grey �“Multidimensional perceptual scaling of musical timbres,” J. Acoust.Soc. Am. 61, 1270 �1977�� showed that sustaining instrument tones equal-ized for level, loudness, and duration are distinguished primarily along threeperceptual dimensions that are strongly correlated with the acoustical di-mensions of: �1� spectral energy distribution, �2� spectral fluctuation, and �3�precedent high-frequency, low-amplitude energy. Following the work ofGrey, we ask listeners having mild to moderately severe sensorineural hear-ing loss to rate pairs of synthetic musical instrument tones according to dis-similarity in aided and unaided conditions. We analyze the dissimilarityjudgments to identify acoustical correlates for the significant dimensions oftimbre discrimination. This analysis helps us to objectively estimate the im-pact of hearing aid signal processing on the ability of hearing-impaired lis-


teners to discriminate among musical instruments, an important componentof musical listening.

11:453aPP11. The perceptual tone-noise ratio of iterated rippled noise inlisteners with hearing loss. Marjorie R. Leek, Sarah Melamed, Michelle R.Molis, and Frederick J. Gallun �Natl. Ctr. for Rehab. Aud. Res., Portland VAMedical Ctr., 3710 SW US Veterans Hospital Rd., Portland, OR 97239�

Previous work has demonstrated that iterated rippled noise �IRN� pro-duces a weaker pitch in hearing-impaired �HI� listeners than in normal-hearing �NH� subjects �e.g., Leek and Summers, 2001�. In this study, thehypothesis was tested that the weaker pitch is a result of an increased per-

ceptual noisiness of IRN for HI subjects. The tone-noise ratio �T/N� was de-veloped by Patterson et al. �1996� to describe the relationship between thestrength of the tone component and the strength of the noise component fora given IRN. The T/N was measured using an adaptive procedure to find thetone-plus-noise level that matched each IRN stimulus. Four NH and 4 HIsubjects took part in the study. The stimuli were IRNs with delays rangingfrom 4 to 16 ms and with one to eight iterations. There was a significanteffect of delay and of iteration number, with longer delays and more itera-tions producing greater T/N. There were no significant differences betweensubject groups. These findings suggest that the weaker complex pitch ob-served in listeners with hearing loss is not due to an abnormally noisy IRNpercept but must be attributed to other impaired processing mechanisms.�Work supported by NIH.�

WEDNESDAY MORNING, 20 MAY 2009 FORUM SUITE, 8:30 A.M. TO 12:00 NOON

Session 3aSA

Structural Acoustics and Vibration: General Structural Acoustics

Rudolph Martinez, ChairCAA-Alion Corp., 84 Sherman St., Cambridge, MA 02140

Contributed Papers

8:303aSA1. Scan-based near-field acoustical holography on partiallycorrelated fields: Theory and numerical experiments.Michael D.Gardner, Kent L. Gee, Alan T. Wall, Scott D. Sommerfeldt �Dept. of Phys.and Astronomy, Brigham Young Univ., N283 ESC, Provo, UT 84602�,Daniel Manwill, and Jonathan D. Blotter �Brigham Young Univ., Provo, UT84602�

Conventional near-field acoustical holography �NAH� requires a coher-ent field. For a coherent source, a scan-based approach can be used with onereference microphone to stitch the phase. For a noncoherent field, scan-based NAH can be performed if the virtual coherence technique is used.This technique uses multiple reference microphones to decompose the par-tial field into mutually uncorrelated partial fields, which are then processedby some NAH method. In particular, the statistically optimized near-fieldacoustical holography �SONAH� method is used with modified Tikhonovregularization. Numerical experiments are performed on a series of pointsources with source strengths chosen to mimic the source characteristics ofhigh-powered jets. The experiments are designed to aid in determining theproper number and location of reference microphones for doing NAH workon high-powered jet noise. �Work supported by Blue Ridge Research andConsulting and the Air Force Research Laboratory.�

8:453aSA2. Scan-based near-field acoustical holography on partiallycorrelated fields: Laboratory experiments. Alan T. W, Michael D.Gardner, Kent L. Gee, Scott D. Sommerfeldt �Dept. of Phys. and Astron.,Brigham Young Univ., N283 ESC, Provo, UT 84602,[email protected]�, Daniel Manwill, and Jonathan D. Blotter �BrighamYoung Univ., Provo, UT 84602�

Forms of near-field acoustical holography �NAH� can be applied tosource reconstructions of arbitrarily correlated extended sources, such as jetexhaust plumes. Prior to implementing NAH to reconstruct the jet noisesource region of a military jet aircraft, laboratory experiments are beingperformed. These experiments utilize statistically optimized NAH�SONAH�, coupled with the virtual coherence method, to reconstruct the ra-diation from correlated, partially correlated, and uncorrelated loudspeakers.Results from these experiments will be shown. Reconstructions of this typerequire the use of multiple reference microphones. However, little is known

about how many should be used or where they should be placed. Successfulreference placement strategies are being explored and commentary on theseresults will also be given. �Work supported by Blue Ridge Research andConsulting and the Air Force Research Laboratory.�

9:003aSA3. Near-field acoustic holography in conical coordinates. TracianneB. Neilsen, Kent Gee, and Michael Gardner �Dept. of Phys., Brigham YoungUniv., Provo, UT 84602, tbn@byu,edu�

Near-field acoustical holography �NAH� techniques can be optimized ifthe method capitalizes on the geometry of the noise source underinvestigation. Helmholtz-equation least squares method �HELS� uses the so-lutions of Helmholtz equation in spherical coordinates as basis functions forthe pressure field. HELS is an efficient NAH technique if the source and themeasurement surfaces are spherical in nature. For nonspherical cases, suchas radiation from a plate or bar, it takes a large number of functions to rep-resent the field. In these cases, there is also a question about where to placethe origin of the wave functions. In search of a HELS-type method thatcould be applied to nonspherical sources, a study into the features of conicalcoordinates has been conducted. Because the Helmholtz equation is sepa-rable in conical coordinates, the solutions can be used, in a manner similarto HELS, as basis functions to represent the pressure field. For conical co-ordinates, the basis functions are spherical Hankel functions and Lamefunctions. This HELS-type formulation in conical coordinates could be anatural choice for NAH on conical sources and may be appropriate for NAHon jet noise. �Work supported by Blue Ridge Research and Consulting andAir Force Research Laboratory.�

9:153aSA4. Determination of ultrasonic vibration modes of a graded solidcylinder using a modified wave-expansion technique. BetsabeManzanares-Martinez �Div. de Ciencias e Ingeniería, Unidad Regional Surde la Universidad de Sonora, Boulevard Lzaro Crdenas 100, Navojoa, So-nora 85880, Mexico, [email protected]�, Jin-Yeon Kim�Georgia Inst. of Technol., Atlanta, GA 30322-0355�, and Arturo Baltazar�CINVESTAV-Saltillo, Ramos Arizpe, Coahuila 25900, Mexico�

Research on wave propagation in cylinders—hollow, solid, orgraded—has been driven by its potential use in the inspection of long-span


engineering structures. Its practical application largely depends on the un-derstanding of modal vibration inside the structure. Typically, the planewave approach is used to model phase velocity, group velocity and disper-sion curves in periodic systems. This proves cumbersome when used tomodel finite periodic structures, semifinite plates, or concentric cylinders.Here, a simpler approach to determine the vibration modes and dispersioncurves of a solid concentric cylinder using a modified wave-expansion ap-proach, used mostly in phononic crystals research, is proposed. The advan-tage of this technique is the possible application on a wide variety of cylin-drical geometries and graded structures with various transverse sections. Theresults of the proposed technique are compared with those obtained by theresonance scattering theory for the simple case of a solid cylinder with asingle core having different mechanical properties. �Work partially spon-sored by SEP-CONACYT through project # 58951.

9:303aSA5. Three component time reversal imaging using nonlinearelasticity. Timothy J. Ulrich, II, Pierre-Yves Le Bas, Robert A. Guyer �LosAlamos Natl. Lab., EES-17, MS D443, Los Alamos, NM 87545,[email protected]�, Brian E. Anderson �Brigham Young Univ., Provo, UT�,Michele Griffa �EMPA, Duebendorf, Switzerland�, and Koen Van DenAbeele �Katholieke Univ. Leuven Campus Kortijk, Kortrijk, Belgium�

The time reversed elastic nonlinearity diagnostic �TREND� has beenshown to have the ability to image near surface nonlinear scatterers �e.g.,cracks and disbonds� using the normal �out of plane� component of motion.This technique has been advanced with the addition of three-componentvector wave field detection using laser vibrometry. This advancement pro-vides the ability of TREND to detect and image features of various orien-tations, increasing its capability and decreasing the likelihood of overlook-ing features due to the inability to excite them. Furthermore, the ability toselectively focus each component of motion provides the means to investi-gate the mechanism of the nonlinear wave generation at the nonlinear scat-tering sites. Experimental data are presented from samples containingknown defects �location and orientation� confirming the sensitivity of three-component time reversal imaging in both linear and nonlinear ultrasonics tofeature orientation.

9:453aSA6. Parameter study for Structural Health Monitoring based onambient noise cross-correlation. Najib Abou Leyla, Emmanuel Moulin,Jamal Assaad, Sebastien Grondel, and Christophe Delebarre �UVHC,IEMN-DOAE, Le Mont Houy, 59313 Valenciennes, France�

The possibility of performing Structural Health Monitoring in aeronauticstructures using ambient noise cross-correlation techniques has been inves-tigated in previous works. The applicability of such methods has been vali-dated by checking the reproducibility and the potential in terms of damagedetection. In this paper, a more detailed description of the acoustic phenom-ena involved is given. The influence of the different parameters �sourcecharacteristics, sensors and damage positions, etc.� on the cross-correlationfunction has been studied. A theoretic study is presented and used to developa simple simulation tool based on multipath reflections of ballistic waves.The simulated results have been successfully compared to finite element re-sults in simple cases. This tool is then exploited to characterize and quantifythe influence of the significant parameters. Finally, some optimization solu-tions of the technique are proposed, and experimentally validated.

10:00—10:15 Break

10:153aSA7. Detection of structural faults in pipelines with time reversal.Nicholas A. O’Donoughue, José M. F. Moura �Dept. of Elect. & Comput.Eng., Carnegie Mellon Univ., 5000 Forbes Ave., Pittsburgh, PA 15217,nodonoug,[email protected]�, and Yuanwei Jin �Univ. of Maryland East-ern Shore, Princess Anne, MD 21853�

The volatile nature of natural gas makes it extremely important to ensurethat transport and distribution pipelines remain free from defects, as leakagecan result in explosions. Current methods for testing buried pipelines rely on

periodic excavation of a section of pipe and attachment of large acoustic ormagnetorestrictive sensors. These systems, while reliable, suffer from a highcost-per-test ratio. To reduce the power requirements, we consider ultra-sound embedded devices that could monitor the pipelines continuously. Theproblem with ultrasound is that, with buried pipes, the propagation is highlydispersive. We propose to use time reversal �TR�, a signal processing tech-nique, to refocus the signals and use, to our advantage, the dispersive natureof the environment. This paper will focus on the modes generated by variousacoustic probing signals and the echoes received with and without TR. Weargue that TR will be most beneficial when there are several dispersivemodes present, a scenario avoided in conventional techniques. We willpresent simulation results for the detection of faults in a pipeline usingPZFlex.

10:303aSA8. Acoustic detection of bolt detorquing in structures. Joe Guarino�Dept. of Mech. and Biomedical Eng., Boise State Univ., Boise, ID 83725-2075, [email protected]� and Robert Hamilton �Boise State Univ.,Boise, ID 83725-2075�

Recent interest in structural health of bridges and large buildings has lentnew urgency to the development and enhancement of theories and methodsin the field of nondestructive testing. We demonstrate a simple technique foracquiring data from an impact test using a basic electronic stethoscope. Thecontinuous wavelet transform �CWT� is used to process and display the tran-sient responses of a bolted joint in a structure with bolts installed in a prop-erly tightened manner and bolts incorrectly installed. Results for tight andloose bolts are compared using the semblance analysis approach describedby Cooper and Cowan �“Comparing time series using wavelet-based sem-blance analysis,” Computers & Geosciences 34, 95–102 �2008��. We en-hance the interpretation of results using speaker-driven audio output synthe-sized from CWT and semblance analysis.

10:453aSA9. Selective excitation of microcantilever array using ultrasoundradiation force. Thomas M. Huber, Daniel C. Mellema, and Brad Abell�Dept. of Phys., Gustavus Adolphus College, 800 College Ave., St. Peter,MN 56082�

The symmetric and antisymmetric eigenstates of a coupled pair of 500956 m length microcantilevers were excited using the ultrasound radiationforce. The excitation was produced using the difference frequency betweenthe two sidebands of a double sideband suppressed carrier AM �DSB-SC-AM� waveform centered on 500 kHz that was emitted by a pair of focusedultrasound transducers. A laser Doppler vibrometer measured the frequencyresponse and deflection shapes of the cantilever pair. When the waveformssent to the transducer resulted in radiation force from both transducers withthe same phase, it excited the 10.00 kHz symmetric state of the cantileverarray while suppressing the 10.17 kHz antisymmetric state. Similarly, whenthe radiation force from the two transducers was 180 degrees out of phase,it selectively excited the antisymmetric state while suppressing the symmet-ric state. This ability to selectively excite different vibrational eigenstates isa unique capability of this noncontact for modal excitation.

11:003aSA10. Limiting performance of active vibration compensation in freemulti-degree-of-freedom mechanical systems. Vyacheslav Ryaboy�Newport Corp., 1791 Deere Ave., Irvine, CA 92606, [email protected]�

Examples of free �not supported� mechanical system requiring active vi-bration control range from space structures to vibration-isolated platformsfor sensitive equipment. While active damping systems reducing resonancevibrations of the structure received significant attention and reached practi-cal implementation, active vibration compensation, or cancellation of forcedvibration, is still problematic in complex systems. In this work, active vi-bration compensation is considered in frame of limiting performance ap-proach that aims at estimating the best results attainable in the whole classof linear multi-degree-of-freedom systems. Several design goals are consid-ered, including absolute and relative displacements of various points of thesystem. The resulting estimates are valid for all possible sets of internal ac-


tive forces. The limiting performance is estimated in terms of frequency do-main and work performed by active forces on system displacements, whichis considered a measure of the control effort. These estimates are expressedas exact inequalities in explicit analytical form. Active force distributionsemerging from limiting performance analyses can assist in finding rationalsystem configurations and optimal controls. Minimum active work, ex-pressed in terms of passive subsystem parameters, provide a criterion foroptimization of a structure as a potential host for an active vibration controlsystem.

11:153aSA11. Response of a simple system made complex by attachingsubsystems—an analytic study. John J. McCoy �School of Eng., TheCatholic Univ. of America, Washington, DC 20064�

A deceptively simple dynamical system comprised of a grounded massto which are attached N, a large number, sprung masses has received muchattention. The reported studies mostly involve physical experiments or nu-merical simulations. Given the large number of physical parameters neededto describe any single system, such a research agenda requires one to ad-dress an excessive number of experiment scenarios. Thus, the motivation forthe analytical study reported. The focus of the study is the net force the at-tached subsystems cause to act on the base system. This force, while “inter-nal” to the coupled system, is a response measure of primary importancesince it accomplishes the work that determines the energy flow to and fromthe base system. As demonstrated, a further reason for the focus is an abilityto construct an asymptotically valid, analytic expression for this responsemeasure. Further demonstrated, using the constructed expression, is a reso-lution of a complex “process,” that describing the energy flow to the system,by the action of an external forcing, and through the system, as a combina-tion of simple “sub-processes.” The resolution requires describing the com-plex process in a time/frequency phase space; the sub-processes are “local”in the phase space.

11:303aSA12. Wave vector method for estimating acoustic vector quantities.Derek C. Thomas and Kent L. Gee �Dept. of Phys. and Astronomy, BrighamYoung Univ., N283 ESC, Provo, UT 84602�

Acoustic vector quantities such as particle velocity and intensity are usu-ally estimated using the finite-difference technique. We present an alternatemethod, termed the wave vector method, for estimating vector quantities inacoustic fields in which the reactive intensity is small relative to the activeintensity. This method utilizes the same equipment necessary for the finite-difference method, yet reduces sensitivity to sensor phase mismatch at lowfrequencies and eliminates bias error at high frequencies. The method is de-veloped for arbitrary sensor configurations, and numerical results are pre-sented for the special case of a regular tetrahedral configuration. �Work sup-ported by NASA Stennis Space Center and STI Technologies.�

11:453aSA13. Impact of spherical probe scattering on estimation of acousticvector quantities. Curtis P. Wiederhold �Dept. of Mech. Eng., BrighamYoung Univ., 435 Crabtree Bldg., Provo, UT 84602,[email protected]�, Kent L. Gee, Derek C. Thomas, Scott D.Sommerfeldt �Brigham Young Univ., Provo, UT 84602�, and Jonathan D.Blotter �Brigham Young Univ., Provo, UT 84602�

Multimicrophone probes are often used to measure energy-based acous-tical quantities. In some cases, these probes consist of microphones mountedon the surface of a sphere, which, due to the high level of symmetry, permitsscattering effects to be better characterized. Scattering of a plane wave in-cident on a rigid sphere has been modeled to observe how particle velocityand intensity calculations are affected by the presence of the sphere. Theseeffects have been investigated for the traditional “finite-difference” methodand a recently developed “wave vector” estimation method. In the computermodel, 3-D surface plots were made showing the calculated error as a func-tion of angle of the incident plane wave and frequency. It is shown that us-ing the wave vector method and purposefully orienting the probe in the pla-nar sound field generally results in the most accurate measurements. �Worksupported by NASA Stennis Space Center and STI Technologies.�

WEDNESDAY MORNING, 20 MAY 2009 GRAND BALLROOM I, 8:00 TO 11:50 A.M.

Session 3aSC

Speech Communication, Musical Acoustics, and Animal Bioacoustics: Source/Filter Interaction in BiologicalSound Production (Lecture/Poster Session)

Ingo R. Titze, ChairDept. of Speech Pathology and Audiology, Univ. of Iowa, Iowa City, IA 52242-1012


Invited Papers

8:05

3aSC1. Modulation of birdsong by resonance filters in the suprasyringeal vocal tract. Roderick A. Suthers �Medical Sci. and Dept.Biology, Indiana Univ., 1001 E. Third St., Bloomington, IN 47405, [email protected]�

The sound generated in the avian vocal organ, the syrinx, is modified by the filter properties of the upper vocal tract before it radiatesfrom the beak as song. Previous investigators have shown that the properties of this vocal tract filter are affected by changes in beakgape, but the basis of this effect remains controversial. In the present study, x-ray cinematography of singing birds was used to inves-tigate the filter properties of the suprasyringeal vocal tract. These experiments show that the dimensions of the oropharynx and esopha-gus are actively controlled during song by motor patterns involving muscles of the hyoid apparatus. These song-related motor patterns,together with movements of the tongue, which modulate the opening from the mouth into the beak, adjust in real time the volume and


dimensions of the oropharynx and cervical esophagus so that the primary acoustic resonance of the upper vocal tract supports and tracksthe fundamental frequency that is being generated by the syrinx. In juvenile Northern Cardinals, these song-related movements of theupper vocal tract first appear during subsong, while the beak is closed, and precede the changes in beak gape that typically accompanyadult song. �Work supported by NIH.�

8:35

3aSC2. Source-filter interactions in birds—Theory and experimental evidence. Gabriel Mindlin, Ezequiel Arneodo �Dept. of Phys.,Univ. of Buenos Aires, [email protected]�, and Franz Goller �Univ. of Utah, Salt Lake City, UT, [email protected]�

The diverse acoustic behavior of birds presents a rich source of natural vocalizations, some of which most likely reflect source-filterinteraction. However, very little experimental evidence exists for the specific role of such interactions in shaping acoustic behavior orthe functional relevance of the resulting acoustic features. As an example of how theoretical approaches can help explain acousticobservations, we discuss coexisting limit cycles in relaxation oscillators subjected to delayed feedback. The dynamical solutions of anonlinear relaxation oscillator subjected to a delayed feedback are analyzed, and the equations under study are designed to model someaspects of the source-tract interaction in birdsong production. By deriving a phase equation for the system and analyzing its solutions,we are able to unveil analytical relationships between the parameters that lead to a variety of solutions. In particular, we study thecoexistence of periodic solutions for similar pitch and first formant frequencies. These dynamical situations allow us to interpret thefrequency jumps present in some birdsong syllables as an effect of the interaction between the source and the tract.

9:05

3aSC3. The epilaryngeal tube and air sacs in mammals as acoustic couplers—A review. Tobias Riede �Dept. of Biology, Univ. ofUtah, 257 S 1400 E, Salt Lake City, UT 84112, [email protected]� and Isao Tokuda �Japan Adv. Inst. of Sci. and Technol., Ishikawa,Japan�

The intralaryngeal space between glottis and the cranial edge of the larynx is called the epilaryngeal tube �synonyms are vestibulumlarynges or supraglottal intralaryngeal space�. Research on larynx models and in humans indicate that this part of the vocal tract filtercan contribute to two important acoustic effects: �a� the singer’s formant and �b� the enhancement of nonlinear source-filter coupling.The acoustic role of this structure in nonhuman mammals is unknown. Furthermore, in many species tube and sac-like cavities areattached to the epilaryngeal tube �laryngeal air sacs� and their function is equally little understood. In this presentation I will report onresults testing the hypothesis that the shape �length and diameter� of the epilaryngeal tube in nonhuman mammals is related to mor-phological parameters �vocal fold morphology, larynx size, body size� and parameters characterizing the species vocal repertoire�repertoire size, maximum sound amplitude, fundamental frequency range, occurrence of nonlinear phenomena�. Preliminary resultsindicate that the length of the epilaryngeal tube is a poor predictor of repertoire characteristics such as maximum sound amplitude andfundamental frequency range. However, species with a prominent epilaryngeal tube produce a large proportion of high fundamentalfrequency call types.

9:35

3aSC4. A possible role of nonlinear source-filter interaction in simulation of childlike speech. Brad H. Story �Dept. Speech, Lang.,Hearing Sci., Univ. of Arizona, P.O. Box 210071, Tucson, AZ 85721�

Simulation �or synthesis� of natural-sounding childlike speech has long been a challenge. This is likely due, at least in part, to anincomplete understanding of the nonlinear interaction of the voice source and the vocal tract filter. Speech production by children istypically characterized by a fairly high fundamental frequency of phonation and a short vocal tract length that produces high formantfrequencies. Together, these two characteristics suggest that low-numbered harmonics �including the fundamental frequency� may often,or even necessarily, be in close proximity to one or more of the formant frequencies. Such conditions may lead to a strong interactionof the acoustic pressures in the vocal tract and the glottal airflow, and possibly the vibration of the vocal folds. The purpose of this studywas to use kinematic models of the vocal folds and vocal tract shape, scaled to approximately represent a 5-year-old child, to generateindividual vowels and sentences. Waveshape and harmonic content of glottal area, glottal flow, and radiated acoustic pressure signalswere compared across three vowels and one sentence. �Research supported by NIH R01-DC04789.�

10:05—10:20 Break

10:20

3aSC5. Nonlinear source-tract interaction in singing. Ingo R. Titze �Dept. of Commun. Sci. and Disord., Univ. of Iowa, WJSHC,Iowa City, IA 52242 [email protected]�

Most approaches to teaching singing are based on concept that there preferred vowel configurations for a given pitch. Speakingvowels are modified not only to create a variety of timbres, but also to support the sound source in self-sustained oscillation. Linear filtertheory, traditionally applied to cans or strengthening by vocal tract coupling, or can it account for source bifurcations in vocal foldoscillation related to vowel selection. Singing are contrasted by selection of two fundamentally different mouth configurations, themegaphone shape and the inverted megaphone shape. With the megaphone shape �used by musical theatre and jazz�, the second har-monic of the sound source is reinforced at all high pitches by keeping the first formant frequency high. With the inverted megaphoneshape �used by classical singers of opera and art song�, the second and third harmonics are reinforced by the second formant. A “lift”of the second harmonic over the first formant becomes a critical skill in acquiring a smooth timbre over a wide pitch range. �Worksupported by NIH.�


Contributed Papers

All posters will be on display from 10:50 to 11:50. To allow contributors an opportunity to see other posters, contributors of odd-numbered papers will be at their posters from 10:50 a.m. to 11:20 a.m. and contributors of even-numbered papers will be at their postersfrom 11:20 a.m. to 11:50 a.m.

3aSC6. Subglottal effects on the vowels across language: Preliminarystudy on Korean. Youngsook Jung �Speech Commun. Group, MIT, Cam-bridge, MA 02139, and Harvard-MIT Div. of Health Sci. and Technol.,Cambridge, MA 02139�

Previous research suggested that subglottal resonances define vowel fea-tures �back� and �low� for English. In testing this hypothesis, we exploredwhether these vowel feature boundaries are independent of language. Aspreliminary research, we made recordings of speech and subglottal signalssimultaneously for several adult Korean speakers. We found acoustic irregu-larities in F1 and F2 near subglottal resonances in Korean vowels. Theboundary between �low� and ��low� vowels agrees with speakers’ firstsubglottal resonances �SubF1�, while the boundary between �back� and��back� agrees with SubF2. In addition, we tested which of these hypoth-eses is correct for a low vowel in Korean, which has only one low vowelwith no contrast of �back� and ��back�: �1� the low vowel is always�back� or �2� SubF2 is avoided but the low vowel is front or back depend-ing on adjacent consonants. The measurements of F2 and F2sub were ob-tained in the context /CaC/, where C is a consonant. We found that SubF2was always avoided for the low vowel. If the adjacent consonants were la-bial or velar, F2 of the low vowel was below SubF2, whereas if the conso-nants were alveolar, F2 of the vowel was above SubF2. �Supported by NIH/NIDCD Grant No. #DC00075.�

3aSC7. Automatic classification of consonant-vowel transitions based onsubglottal resonances and second formant frequencies. Nancy F. Chenand Steven M. Lulich �Speech Commun. Group, MIT, 77 MassachusettsAve., Cambridge, MA 02139�

A growing body of work indicates that subglottal resonances �SGRs� di-vide the frequency space of vowels and consonants into distinct regions inseveral languages �S. Lulich, J. Phonetics �in press�, and references therein�.For instance, the second formant frequency �F2� of back vowels lies be-tween the first and second subglottal resonances �Sg1 and Sg2�, while forfront vowels F2 lies at higher frequencies than Sg2. In alveolar stop bursts,F2 lies between Sg2 and the third subglottal resonance �Sg3�. In this study,we build on previous work �S. Lulich, JASA 124, 2558 �2008�� to automati-cally determine SGRs using locus equations computed from 405 consonant-vowel �CV� transitions produced by an adult male native speaker of Ameri-can English. Consonants and vowels are then classified into place ofarticulation and front/back features based only on the relations between F2and the SGRs. The mean hit rate across categories was 77%, while the meanfalse alarm rate was 12%. These results show relative improvements of missand false alarm rates by 21% and 14% from a baseline experiment, whereF2 without SGRs was used to perform the classification. Our knowledge-based approach of classifying CV transitions is potentially useful whenvowel and consonant identities are unavailable.

3aSC8. Source-filter interaction in the opposite direction: Subglottalcoupling and the influence of vocal fold mechanics on vowel spectraduring the closed phase. Steven M. Lulich �Speech Commun. Group, MIT,77 Massachusetts Ave., Cambridge, MA 02139, [email protected]�,Matias Zanartu �Purdue Univ., West Lafayette, IN 47907�, Daryush D. Me-hta �Harvard-MIT Div. of Health Sci. and Technol., Cambridge, MA 02139�,and Robert E. Hillman �Harvard Med. School, Boston, MA 02114�

Studies of speech source-filter interaction usually investigate the effectof the speech transfer function �loading� on vocal fold vibration and thevoice source. In this study we explore how vocal fold mechanics affect thetransfer function throughout the glottal cycle, with emphasis on the closedphase. Coupling between the subglottal and supraglottal airways is modu-lated by the laryngeal impedance. Although coupling is generally thought tooccur only during the open phase of vocal fold vibration, a posterior glottalopening and the vocal fold tissue itself can allow sound transmission,thereby introducing coupling during the closed phase as well. The imped-ance of the vocal fold tissue at closure is shown to be small enough to per-mit coupling throughout the phonatory cycle, even in the absence of a pos-

terior glottal opening. Open- and closed-phase coupling is characterizedusing mathematical models of the subglottal and supraglottal airways, andthe parallel laryngeal impedances of the membranous glottis, posterior glot-tal opening, and vocal fold tissue. Examples from sustained vowels are pre-sented, using synchronous recordings of neck skin acceleration, laryngealhigh-speed videoendoscopy, electroglottography, and radiated acousticpressure.

3aSC9. Nonlinear flow-structure coupling in a mechanical model of thevocal folds and the subglottal system. Michael S. Howe �College of Eng.,Boston Univ., 110 Cummington St., Boston, MA 02215� and Richard S.McGowan �CReSS LLC, Lexington, MA 02420�

An analysis is made of the nonlinear interaction between flow in a me-chanical model of the subglottal vocal tract and a model of the vocal folds.The mean flow through the system is produced by a “lung cavity” that isassumed to be steadily contracting. The lungs are connected to a subglottaltube of length L. The model for the vocal folds is at the other end of thesubglottal tube. This model is a simple, self-exciting single-mass mathemati-cal model of the vocal folds used to investigate the sound generated withinthe subglottal domain and the unsteady volume flux from the glottis. In thecase when the absorption of sound by the lungs is presumed small and whenthe subglottal tube behaves as an open ended resonator �when L is as largeas half the acoustic wavelength� a mild increase in volume flux is predicted.However, the strong appearance of second harmonics of the acoustic field ispredicted at intermediate lengths, when L is roughly a quarter of the acousticwavelength. In the cases of large lung damping, however, only modestchanges in volume flux are predicted to appear. �Work supported by DC-009229 to UCLA under subcontract.�

3aSC10. An impedance-based inverse filtering scheme with glottalcoupling. Matias Zanartu �School of Elect. and Comp. Eng., Purdue Univ.,206 S. Martin Jischke Dr., West Lafayette, IN 47907,[email protected]�, Julio C. Ho �Purdue Univ., West Lafayette, IN47907�, Daryush D. Mehta �Harvard-MIT Div. of Health Sci. and Technol.,Cambridge, MA 02139�, Robert E. Hillman �Massachusetts General Hospi-tal, Boston, MA 02114�, and George R. Wodicka �Purdue Univ., West Lafay-ette, IN 47907�

Source-filter interactions in voice production arise from considering fi-nite glottal impedances that are comparable with that of the vocal tractand/or the subglottal system. Besides the changes in the source behavior,finite glottal impedances also allow for acoustic coupling between the sub-glottal and supraglottal tracts. Vowel dependence on the subglottal acousticpressure is evident in recordings of skin acceleration overlying the supraster-nal notch. To obtain estimates of other physiologic signals from skin accel-eration, an impedance-based inverse filtering scheme that considers acousticcoupling is proposed. The scheme is based on an electrical analog model ofa dipole source and assembles multiple approaches to estimate the systemimpedances. An experimental platform considers simultaneous measure-ments of skin acceleration, flexible high-speed videoendoscopy, oral volumevelocity, intraoral pressure, electroglottography, and radiated acousticpressure. Recordings of sustained vowels, co-articulated gestures, and pitchglides provide a comprehensive data set to study tract coupling and source-filter interactions. Preliminary results provide insights into the interrelationamong the measured signals and illustrate the tissue instabilities of the vocalfolds during some of the gestures. Further evaluation in cases of vocal foldpathology is also planned, where source-filter interactions are expected to beeven more pronounced.

3aSC11. Vocal inharmonicity analysis: A promising approach foracoustic screening for dysphonia. Samuel Matteson �Dept. of Phys., Univ.of North Texas, 1155 Union Circle 311427, Denton, TX 76203-5017,[email protected]� and Fang-Ling Lu �Univ. of North Texas, Den-ton, TX 76203-5017�


In the United States, 6.8% of men, women, and children report voiceproblems currently, while during their lifetime ca. 29% will complain ofsome dysphonia, often due to pathologies of the vocal folds. The authors �aphysicist and a speech pathologist� describe an interdisciplinary approachthat exhibits promise for detecting physiological abnormalities of the vocalfolds from a spectral analysis of the overtone series of spoken tokens. Thispreliminary investigation shows that the normal human vocal fold emitsovertones that are very nearly precise integral values of the fundamental.Physiological problems of the vocal folds, however, introduce mechanicalnonlinearities that manifest themselves as frequency deviations from theideal harmonic �that is, integral� values. The authors quantify this inharmo-nicity, describing and illustrating how one can efficiently obtain and analyzesuch data. They outline, as well, a proposed investigation to assess the clini-cal sensitivity and significance of the analysis discussed in this work in con-junction with laryngoscopic diagnosis of pathology.

3aSC12. Geometric dependence of phonation threshold pressure andphonation onset frequency. Zhaoyan Zhang �UCLA School of Medicine,31-24 Rehab Ctr., 1000 Veteran Ave., Los Angeles, CA 90095-1794�

Dependence of phonation threshold pressure and phonation onset fre-quency on vocal fold geometry was numerically investigated in a continuummodel of the vocal folds. The geometric parameters of interest include themedial surface thickness, vocal fold depths of the body, and cover layers.Changes in these parameters may occur either due to laryngeal muscle ac-tivation, vocal pathology, or aging. Simulations show that both thresholdpressure and onset frequency increased with decreasing vocal fold depth.However, depending on glottal geometry, increasing medial surface thick-ness may either increase or decrease phonation threshold pressure andfrequency. Variation of the medial surface thickness also led to phonationonset occurrence at a different eigenmode, leading to sudden changes in on-set frequency and vocal fold vibration pattern. These numerical predictions

were further supported by experiments using a self-oscillating physicalmodel. The result of this study confirms previous findings that phonationonset occurs as a matching between the flow stiffness, which is proportionalto subglottal pressure, and vocal fold stiffness, which scales with natural fre-quency squared and depends on geometry and boundary conditions of thevocal fold structure as well as material properties of the vocal folds. �Worksupported by NIH.�

3aSC13. Analysis and synthesis of humpback whale songs. Pranab K.Dhar, Sangjin Cho, Jong-Myon Kim, and Uipil Chong �Univ. of Ulsan, Ul-san 680-749, Korea�

The humpback whale song is one of the most complex, non-human,acoustic displays in the animal kingdom. In this paper, we analyze and syn-thesize the humpback song using additive synthesis which is one of the mostpowerful techniques for the analysis, modification, and synthesis of complexaudio or speech signals. This method creates complex sounds by adding to-gether individual sinusoidal signals called “partials.” A partial’s frequencyand amplitude are each time-varying functions, so it is a more flexible ver-sion of the harmonic associated with a Fourier series decomposition of aperiodic waveform. Applying the fast Fourier transform to all overlappingframes �small time segments�, we can detect peaks from the frequency spec-trum of each frame and calculate the frequency, magnitude, and phase for allthe peaks. These extracted parameters are then used as components of thesinusoidal signals �partials� for the synthesis process. This process finallyreconstructs and concatenates each frame, generating the synthesized hump-back song. We observed that this synthesized song resembles much moreclosely the original humpback song by the time/frequency domain represen-tation and listening. In the future, we will analyze and synthesis other baleenwhale songs with this powerful synthesis method. �Work supported by IITA�IITA-2008-�C1090-0801-0039��.�

WEDNESDAY MORNING, 20 MAY 2009 PARLOR B/C, 7:45 TO 11:30 A.M.

Session 3aSP

Signal Processing in Acoustics and Acoustical Oceanography: Poroelastic Materials: Models, Bounds, andParameter Estimation

Max Deffenbaugh, ChairExxonMobil Research & Engineering Co., 1545 Route 22 East, Annandale, NJ 08801


Invited Papers

7:50

3aSP1. Acoustics in granular porous media and the consolidation continuum. James G. Berryman �Earth Sci. Div. Lawrence Ber-keley Natl. Lab, One Cyclotron, Dr. Berkeley, CA 94720, [email protected]�

One key influence on acoustic wave propagation in granular porous media is the degree to which the solid constituent grains can betreated as fully consolidated, weakly and/or partially consolidated, or entirely unconsolidated. Well-known results of Gassmann and Biotall implicitly assume that the medium is fully consolidated, with welded contacts at the grain-to-grain interfaces. Such implicit assump-tions are also present in standard bounding methods for elastic behavior, such as the Hashin-Shtrikman bounds of elasticity. Influenceof reductions in the degree of consolidation can be quantified for partially or weakly consolidated media, and granular media having nowelded contacts can also be treated as porous media for sound waves in the Biot-Gassmann sense when grains are experiencing suf-ficient overall confining stress. Methods recently developed to quantify wave propagation characteristics over the full range of possiblebehaviors in grain packs, as well as comparisons to experiments, will be presented.


8:20

3aSP2. Fabric dependence of poroelastic wave propagation. Stephen Cowin and Luis Cardoso �Dept. of Biomed. Eng., The CityCollege, NY, NY 10031, [email protected]�

The governing equations for wave motion in the linear theory of anisotropic poroelastic materials are developed and extended toinclude the dependence of the constitutive relations upon fabric. Fabric is a quantitative stereological measure of the degree of structuralanisotropy in the pore architecture of a porous medium. With the addition of the second order symmetric tensor fabric variable, theformulation of wave motions in the poroelastic theory is consistent with the presentations of Biot and later authors. The dependence ofall the material tensors in the Biot theory on the fabric tensor aligns the material tensors, so when a single direction that is a plane ofmaterial symmetry is selected, the equations simplify considerably. The customary polynomial of the sixth deg for the wave speeds ofthe anisotropic Biot theory in a selected direction reduces to three quadratic equations to solve for the wave speeds and attenuation.While the theory is applicable to any saturated porous material, the two longitudinal waves predicted by this model are measured incancellous bone and used to derive the corresponding anisotropic elastic constants. Representative examples of bone loss are analyzedas a function of the porosity, tissue density, and fabric.

8:50

3aSP3. Anisotropic bone loss characterized using fabric-based poroelasticity. Luis Cardoso and Stephen Cowin �Dept. of Biomedi-cal Eng., The City College, 138th St., and Convent Ave., NY, NY 10031, [email protected]�

The current gold standard to assess bone loss is the bone mineral density �BMD� test, performed with a dual x-ray absorptiometrysystem. BMD measurements are highly correlated to bone mass when measured in spine, wrist, and femoral neck. However, the BMDcannot fully explain the decrease in bone strength and the associated risk of fracture because bone loss is not homogeneous, and doesnot depend on mass changes only. In this study, a fabric-based poroelastic model is used to determine the elastic constants of bone thathave undergone disuse-osteoporosis and bone treated with an antiresorptive drug. Images from microCT are used to determine theporosity, density, and fabric on each group of specimens. These measurements are used in the proposed fabric-based poroelastic modelto determine the sample’s anisotropic elastic constants. These elastic constants are then compared to the ones obtained by ultrasoundwave propagation measurement as previously described in the Cowin and Cardoso presentation. Image analysis and ultrasound wavepropagation are both shown able to determine changes in anisotropic elastic constants during bone loss when used with the proposedanisotropic poroelastic model. This study provides the foundation to define a bone quality criterion beyond the sole determination ofbone mass.

Contributed Paper

9:203aSP4. Effective medium models from x-ray microtomography images.Max Deffenbaugh, John Dunsmuir �ExxonMobil Res. and Eng. Co., 1545Rte. 22 East, Annandale, NJ 08801, [email protected]�,Shiyu Xu �ExxonMobil Exploration Co., Houston, TX 77060�, and Enru Liu�ExxonMobil Upstream Res. Co., Houston, TX 77252�

A novel method is described where an effective medium model is gen-erated from a 3-D x-ray microtomography image of a rock sample. In con-trast to current modeling practice, material phases are not assigned idealizedgeometries, like spheroids. Instead, strain concentration tensors are com-puted numerically for the true phase geometries observed in the 3-D image.

In this method, a 3-D image of x-ray attenuation is converted into a 3-Delastic properties volume, the strain field is computed within the volume,and the strain concentration tensors, which quantify the contribution of eachgrain and pore type to the bulk elastic properties, are calculated from thestrain field. From only one representative sample of a rock type and with noassumptions about grain or pore shape, an effective medium model is gen-erated that specifies the effective elastic tensor as a function of the variousmineral and pore volume fractions. The method is demonstrated by gener-ating effective medium models for several rock types. These models can beused in hydrocarbon exploration to relate the velocities of seismic waves ina poroelastic reservoir to the porosity, structure, and composition of the rockmatrix and the type and distribution of the fluid within the pore spaces.

Invited Papers

9:35

3aSP5. Model parameter estimation of a porous seabed using in situ acoustic-probe and chirp-sonar reflection data. Altan Turgut�Naval Res. Lab., Acoust. Div., Washington, DC 20375�

The velocity dispersion and frequency dependency of attenuation in marine sediments are two important measures that provide theability to test the validity of geoacoustic models as well as to estimate physical properties from the acoustic data. A widely-used Bi-ot–Stoll theory for elastic-wave propagation in porous marine sediments seems to predict a narrow band of dispersion that was measuredonly in well-sorted granular marine sediments �A. Turgut and T. Yamamoto, J. Acoust. Soc. Am. 87, 2376–2382 �1990��. Recent mea-surements in silty-sand sediments show almost linear frequency dependency of attenuation and mild velocity dispersion within the 3–80kHz frequency band. The newly measured attenuation and velocity dispersion curves are in good agreement with those predicted by anextended Biot theory for sediments with a distribution of pore sizes �T. Yamamoto and A. Turgut, J. Acoust. Soc. Am. 83, 1744–1751�1988��. Simultaneous measurements of in situ acoustic-probe data and chirp-sonar reflection data are also used to estimate the modelparameters of the extended Biot model. �Work supported by the Office of Naval Research.�

10:05—10:15 Break


10:15

3aSP6. Cancellous bone as a poroelastic medium: Extracting underlying material properties from improved ultrasonicmeasurements of frequency dependent attenuation and phase velocity. James G. Miller, Christian C. Anderson, Adam Q. Bauer,Karen Marutyan, G. Larry Bretthorst, Mark R. Holland �Washington Univ., 1 Brookings Dr., St. Louis, MO 63130�, Brent K. Hoffmeis-ter �Rhodes College, Memphis, TN 38112�, and Keith A. Wear �U.S. Food and Drug Administration, Silver Spring, MD 20993�

Cancellous bone can be modeled as a poroelastic medium consisting of a viscous fluid �marrow� and a stiff framework �trabeculae�.Transmission of ultrasound through bone can result in fast and slow waves as well as mode conversion and multiple scattering, all ofwhich can mask the underlying material properties of bone that determine fracture risk. Phase cancellation at the receiving transducerand interference effects in the field can further compromise the potential of bone sonometry for assessing bone quality. The attenuationcoefficient is observed to increase approximately linearly with frequency, a fact that accounts for the use of broadband ultrasoundattenuation �BUA� to characterize bone. Many laboratories report that the phase velocity of ultrasonic waves propagating through can-cellous bone decreases with increasing frequency �negative dispersion�. However, an increase in phase velocity with frequency �positivedispersion� would be expected based on the causality-imposed Kramers–Kronig relations. This apparent negative dispersion in bone canarise from interference between fast wave and slow wave longitudinal modes. Interference and phase cancellation at the receiver canalso be sources of artifactual alterations in the attenuation and phase velocity. �Work supported in part by NIH R37HL40302R01AR057433, NSF CBET-0717830�.

Contributed Papers

10:453aSP7. Successful use of Bayesian inference to obtain the fast and slowwave properties of cancellous bone from sonometry measurements.Christian C. Anderson �Washington Univ., 1 Brookings Dr., St. Louis, MO63130�, Michal Pakula, Pascal Laugier �Univ. Paris 6, 75006 Paris, France�,Adam Q. Bauer, Karen Marutyan, G. Larry Bretthorst, Mark R. Holland,and James G. Miller �Washington Univ., St. Louis, MO 63130�

Clinical trials have demonstrated that frequency dependent attenuation�broadband ultrasound attenuation, �BUA�� and speed of sound �SOS� pro-vide an assessment of fracture risk. Previous studies from our laboratory ofthe “forward problem” show that the negative dispersion observed in can-cellous bone can arise when signals consisting of overlapped fast and slowwaves are analyzed as if only one wave is present. The present study exam-ines the “inverse problem” using Bayesian probability methods suitable forrecovering the underlying material properties from received transmissionsonometry signals complicated by the presence of multiple signals. Trans-mission studies were carried out on bone mimicking phantoms and on speci-mens of femur condyles. Received rf signals served as input to our Bayesianalgorithm. The program that implements the Bayesian calculations recon-structs the individual fast and slow waves and constructs the model outputfrom parameters that maximize the joint posterior probability. Composite rfsignals constructed by summing these waves were in excellent agreementwith signals transmitted through bone-mimicking phantoms and were ingood agreement with signals transmitted through bone samples despite theadditional complexities arising from ultrasound propagation through thecomplex trabecular network. �Work supported in part by NIH R37HL40302R01AR057433, and NSF CBET-0717830�.

11:003aSP8. Geoacoustic inversion performed from two source-receive arraysin shallow-water waveguide. Alexey Sukhovich, Philippe Roux, and MarcWathelet �LGIT, UMR CNRS 5559, Univ. Joseph Fourier, Grenoble, France,[email protected]�

Raylike propagation of acoustic waves in a shallow-water waveguide be-tween two vertical line arrays is investigated by applying a double beam-

forming algorithm, which performs time-delay beamforming on both emit-ting and receiving arrays and allows identification of eigenrays by theiremission and reception angles and arrival times. From the intensity of eacheigenray, it is possible to determine reflection coefficient from the bottom ofthe waveguide as a function of an angle of incidence. The procedure wasinitially tested in a small-scale tank experiment for an acoustic waveguidewith either steel or Plexiglas bottom. By fitting an experimentally found re-flection coefficient with a corresponding theoretical expression, an estimatefor the speed of shear waves in the bottom material was obtained. Similaranalysis was subsequently applied to the data obtained during an at-sea ex-periment, which was performed between two vertical transducer arrays inshallow-coastal waters of the Mediterranean. An angle-dependent bottom re-flection coefficient was extracted and geoacoustic inversion was performedby fitting the data with theoretical calculations, in which bottom sedimentswere modeled as a multilayered system. Good agreement between experi-ment and theory was observed. Our results indicate possible application ofeigenray intensity analysis based on double beamforming algorithm forgeoacoustic inversion problems.

11:153aSP9. Monitoring stress related velocity variation in concrete with a2�10�5 relative resolution using diffuse ultrasound. Larose Eric �Lab. deGeophys. interne et Tectonophysique, CNRS & Univ. J. Fourier, Grenoble,France� and Hall Stephen �CNRS & Grenoble Univ., Grenoble, France�

Ultrasonic waves propagating in solids have stress-dependent velocities.The relation between stress �or strain� and velocity forms the basis of non-linear acoustics. In homogeneous solids, conventional time-of-flight tech-niques have measured this dependence with spectacular precision. In hetero-geneous media such as concrete, the direct �ballistic� wave around 500 kHzis strongly attenuated and conventional techniques are less efficient. In thismanuscript, the effect of weak stress changes on the late arrivals constitutingthe acoustic diffuse coda is tracked. A resolution of 2�10�5 in relative ve-locity change for stress change is attained. We are thus sensitive to stresschange much lower than 50 kPa. This provides an original way to measurethe nonlinear parameter with relatively small stress variations �less than 100kPa�.


WEDNESDAY MORNING, 20 MAY 2009 PAVILION WEST, 8:00 TO 11:55 A.M.

Session 3aUW

Underwater Acoustics and Acoustical Oceanography: Physics-Based Undersea Clutter Model Verificationand Validation I

Juan I. Arvelo, CochairApplied Physics Lab., Johns Hopkins Univ., Laurel, MD 20723-6099

Kenneth G. Foote, CochairWoods Hole Oceanographic Inst., Woods Hole, MA 02543

Timothy K. Stanton, CochairDept. of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Inst., Woods Hole, MA 02543


Invited Paper

8:05

3aUW1. Dynamic and acoustic modeling of discrete biologics for active sonar simulation. Brian R. La Cour and John E. Hamann�Appl. Res. Labs., The Univ. of Texas at Austin, P.O. Box 8029, Austin, TX 78713-8029�

A model is proposed for simulating the group dynamics and acoustic echoes of aggregate, discrete biologics in midfrequency �2–5kHz� active undersea sonar. Using a Lagrangian description, group behavior is modeled by a set of Newtonian forces and stochasticperturbations on a collection of point masses. Interactions comprise a grouping force, which gives a characteristic separation distance,and an arrayal force, which tends to align the velocities of the group’s constituents. The group dynamics is characterized in terms oftheir statistical and asymptotic properties and studied as a function of the model parameters. Several models for the acoustic responseare considered and studied for both individual and aggregate response. Finally, the resulting synthetic echoes are compared against thoseof actual biologics measured on a midfrequency active sonar system. The synthetic echoes are found to reproduce well both the quali-tative characteristics of measured biologics and the resulting tracking and classification features found in a typical active sonar signaland information processing chain.

Contributed Paper

8:253aUW2. Coherent backscattering effect from mid-frequencyreverberation measurements in shallow-water. Karim G. Sabra �School ofMech. Eng., Georgia Inst. of Technol., 771 Ferst Dr. NW, Atlanta, GA30332-0405�

The coherent backscattering �or backscattering enhancement� effect is apersistent interference effect which occurs between waves propagating inrandom media such as randomly distributed scatterers and rough surfaces.Previous experimental and theoretical studies in optics, acoustics, or seis-mology have demonstrated that the coherent backscattering results in a dou-bling of the recorded intensity reflected exactly in the backward direction

with respect to any other direction. We will present experimental observa-tions of the coherent backscattering effect from mid-frequency reverberationdata �3–4 kHz� collected in shallow water off the west coast of Italy usingvarious sensor array configurations. This demonstrates the presence of co-herent effects in shallow water reverberation recordings from rough sea-beds. Hence, coherent reverberation effects need to be accounted for to ob-tain accurate predictions of sea clutter levels. Furthermore, accuraterendering of the coherent backscattering effect could be used to simplyverify and validate physics-based undersea clutter models. Practical imple-mentation for the design of active sonar systems will be discussed. �Worksupported by ONR, Code 321.�

Invited Papers

8:40

3aUW3. Measurements and modeling of midfrequency clutter from fish aggregations over Georges Bank in the Gulf of Maine.Roger C. Gauss, Joseph M. Fialkowski, Richard Menis, Edward L. Kunz �Naval Res. Lab., Code 7140, Washington DC 20375-5350,[email protected]�, Timothy K. Stanton, Cynthia J. Sellers �Woods Hole Ocean. Inst., Woods Hole, MA 02543�, and J. MichaelJech �NOAA NE Fish. Sci. Ctr., Woods Hole, MA 02543�

Broadband midfrequency acoustic measurements of fish backscattering were made with two complementary sonar systems in Sep-tember 2008 at the northern slopes of Georges Bank in the Gulf of Maine. One system, towed near the surface, was downward-looking�short-range: � 0.2 km� and was used to image fish at high vertical resolution throughout the water column. The other system washorizontal-looking �relatively long-range: 1–10 km�, consisting of a vertical source array and a horizontal receive array, and was usedto image fish at high horizontal resolution. In this talk, the focus is on characterizing the longer-range data. Spectrogram analysisshowed that the echoes had resonance frequencies in the 2–4 kHz band, consistent with scattering by Atlantic herring, while examina-tion of normalized match-filter output revealed strong, spatiotemporally variable clutter. The associated probability-density functions


�PDFs� exhibited variable non-Rayleigh behavior. Several PDF models were fit to the data, with the K and Poisson-Rayleigh PDFmodels providing not only good fits, but physical insights into the clutter process �such as estimates of the expected number of discretescatterers per unit area�. These results provide an improved understanding of both fish behavior and the characteristics of fish aggre-gations as long-range clutter fields. �Work supported by ONR.�

9:00

3aUW4. Bioalpha, transmission loss and validation of scattering models in biologically intense shallow water environments. OrestDiachok �Appl. Phys. Lab. Johns Hopkins Univ., Laurel, MD 20723-6099�

Scattering and extinction by fish swim bladders are manifestations of the same phenomenon. Scattering causes reverberation fromdispersed fish and distinct echoes from fish schools �clutter�, and diminishes the magnitude of transmitted signals. The biological ex-tinction coefficient �bioalpha� has been shown to have a large effect on transmission loss �TL� in several biologically intense, shallowwater environments, including the Bristol Channel �Weston �1967��, Yellow Sea �Qiu et al. �1999��, Gulf of Lion �Diachok �1999��, andSanta Barbara Channel �Diachok �2005��. Consequently, models of biological scattering must include the effects of bioalpha on TL inshallow water environments. The objectives of this paper are to review the experimental evidence of the effects of bioalpha on TL, andto describe and demonstrate the effectiveness of an analytical approach to modeling this phenomenon. Since it is not possible at presentto predict the effects of bioalpha on TL from first principles �distributions of swim bladder dimensions, spatial distributions of numberdensities, and timing of diurnal changes in school structures and seasonal migration patterns are only approximately predictable�, ex-periments designed to demonstrate the validity of scattering models in biologically intense, shallow water environments should includeconcurrent broadband TL measurements during both night and day.

Contributed Paper

9:203aUW5. Statistics of echoes from a directional sonar beam insonifyingfinite numbers of single scatterers and patches of scatterers. DezhangChu �NOAA/NMFS/Northwest Fisheries Sci. Ctr., Seattle, WA 98112� andTimothy K. Stanton �Woods Hole Oceanograph. Inst., Woods Hole, MA02543�

When a sonar beam sweeps across a field of scatterers, the echoes canfluctuate significantly from ping to ping. The fluctuations can be stronglynon-Rayleigh because: �1� there can be a small number of scatterers in thebeam; �2� the distribution of scatterers can be inhomogeneous or “patchy;”and �3� the echoes are weighted by the nonuniform response of the sonarbeam. In this paper, a general formulation combining equations derived by

Ehrenberg �Proc. Conf. Eng. Ocean Environ. 1, 61–64, �1972�� and Barakat�Optica Acta 21, 903–921, �1974�� is developed to account for a directionalsonar beam involving an arbitrary finite number of scatterers, each with anarbitrary echo probably density function �PDF� and randomly located in thebeam. Theoretical predictions are made, along with numerical simulationsfor validation, for a range of conditions, including: �1� different number ofscatterers arbitrarily located in the beam and �2� different echo PDFs of thescatterers. Here, a “scatterer” could be an individual or a patch of scattererswhose dimensions are much smaller than the footprint of the sonar beam.Although the application is intended for volumetric patches, the formulationcould be applied to areal patches under appropriate conditions. �Work sup-ported by ONR.�

Invited Papers

9:35

3aUW6. Comprehensive, integrated database of elements contributing to bottom and volume clutter. Kathleen J. Vigness-Raposa,William T. Ellison, Adam S. Frankel, David Zeddies, Cheryl L. Schroeder �Marine Acoust., Inc., 809 Aquidneck Ave., Middletown, RI02842, [email protected]�, Peter V. August, Christopher Damon, and Charles LaBash �Univ. of Rhode Island,Kingston, RI 02881�

Multiple components within and at the bottom of the water column can scatter acoustic signals, resulting in decreased sonar per-formance and compromised tactical decision making. Many of the biological organisms that contribute to acoustic clutter are also pro-tected or managed species, integral to a fully functional marine ecosystem. In order to understand, predict, and model bottom andvolume scattering, detailed descriptions of the spatial, spectral, and temporal variability of clutter elements are needed, along withreliable estimates of backscattering strength. All of these necessary components are dependent on marine wildlife databases. Efforts byseveral organizations have resulted in databases that provide pieces of the overall puzzle. Databases of distribution and abundance�Census of Marine Life’s OBIS-SEAMAP�, two-dimensional movement �Census of Marine Life’s Tagging of Pacific Pelagics�, anddiving and movement behavior �Marine Wildlife Behavior Database� are examples of current, but disparate, projects. Ongoing effortsare consolidating inputs from such databases to predict realistic, spatially dependent bioclutter animats. By linking geospatial featuresof clutter elements in training and mission planning systems, sonar operators and designers can better predict and analyze the occurrenceof target-like clutter. �Work supported by NAVSEA SBIR, ONR STTR, and NOAA.�

9:55—10:15 Break

10:15

3aUW7. Modeling persistent clutter. Bruce K. Newhall �Johns Hopkins Univ., Appl. Phys. Lab, 11100 Johns Hopkins Rd., Laurel,MD 20723�

Clutter is the collection of targetlike returns from nontarget sources that are observed in active sonar use. Persistent clutter is the setof clutter returns that persist across multiple transmissions and thereby form false target tracks in sonar processing. The U.S. Navy isdeveloping active sonar simulators for training purposes. Effective training requires physically realistic clutter simulation includingmodeling of persistent clutter. Potential physical sources of persistent clutter are discussed, and a variety of modeling approaches arereviewed. Measures of effectiveness for model comparison with persistent clutter data are given.


10:35

3aUW8. Exploring spatiotemporal distribution as a clutter simulation validation measure. Juan I. Arvelo, Jr. �The Johns HopkinsUniv., Appl. Phys. Lab., 11100 Johns Hopkins Rd., Laurel, MD 20723-6099�

The amplitude distribution is widely used to compare modeled and measured undersea clutter �J. Arvelo et al., JASA 120, 3381�2006��. However, additional validation measures must be identified to ensure that clutter models are suited to realistically simulateactive sonar displays and accurately emulate tracker performance. For example, the amplitude distribution ignores the stochastic ar-rangement of clutter at various space/time scales �V. Lupien, JASA 105, 2187–2282 �1999��. Active midfrequency vertical line arraydata from the ASIAEX 2001 experiment in the East China Sea is processed to explore the suitability of the clutter spatiotemporaldistribution as a key validation measure. The vertical array permitted the separation of bottom from surface generated clutter. A physics-based seafloor clutter model �B. Newhall and J. Arvelo, JASA 118, 2041 �2005�� was implemented to simulate the experimental scenariowith known measured and inferred environmental conditions. Comparisons of the measured and simulated amplitude and spatiotem-poral distributions uncovered significant effects that must be included to improve existing clutter models. �This effort was conductedunder the auspices of the Undersea Warfare Business Area Independent Research and Development program of the Johns HopkinsUniversity Applied Physics Laboratory.�

10:55

3aUW9. Midfrequency active sonar clutter statistics segregated by broad clutter types. James M. Gelb �Appl. Res. Labs., UTAustin, 10000 Burnet Rd., Austin, TX 78758, [email protected]�

The empirical distributions of normalized matched-filter echoes from a midfrequency active sonar with hyperbolic frequency-modulated waveforms in a myriad of oceanic environments are studied for three broad clutter classes: bottom structures, diffuse com-pact clutter �e.g., seaweed�, and compact nonstationary clutter �e.g., biologics�. The distributions are characterized using the K distri-bution and the generalized Pareto distribution. Methods of parameter estimation are discussed, and parameters are computed for smallsubregions of the clutter fields. A plot of the Kolmogorov–Smirnov goodness-of-fit statistic of individual subregions is presented foreach model and class to highlight the versatility of the models when applied to large quantities of data. Cumulants are computed fromthe data and are utilized as features in a classifier to demonstrate separability between the classes. An important aspect of this work isthe use of distinct clutter classes as opposed to collectively characterizing all clutter as reverberation. Environmental effects are notconsidered, as the goal of this work is to determine the utility of local clutter estimation models in practical sonar processing systemswhere accurate environmental data is unavailable. �This work is sponsored by the Office of Naval Research undersea signal processingdiscovery and invention program.�

11:15

3aUW10. Simulation of rippled-sand sonar imagery with visual and statistical verification. Shawn F. Johnson �Graduate Prog. inAcoust., Appl. Res. Lab., 117 Appl. Sci. Bldg., State College, PA 16804�

Synthetic aperture sonar �SAS� imagery is often characterized by a decidedly non-Rayleigh pixel amplitude distribution, owing toits inherent high-resolution combined with speckle induced by the coherent image formation process. Recent work has shown increasingthe resolution cell size by limiting the image bandwidth typically produces images with statistics tending toward a Rayleigh distribution.A caveat to this generalization is that the trend toward Rayleigh is dependent on orientation of the SAS system to strongly correlatedsea-floor structures such as sand-ripples. A method has been developed to simulate rippled-sand sonar imagery at high-frequencies �i.e.,on the order of 100 kHz�, which accounts for nonsymmetric ripple shape, sediment acoustic properties, sonar to ripple orientation,system resolution, and coherent imaging induced speckle. This numerical simulation method is computationally inexpensive and com-pares well both visually and statistically with collected data over a wide range of orientation angles. Simulation methods will be pre-sented with verification using SAS imagery collected by the Naval Surface Warfare Center: Panama City Division. �Work supported byONR Grants No. N00014-04-1-0013 and No. N00014-06-1-0245, and Code 32.�

11:35

3aUW11. Experimental tests of models for high-frequency scattered envelope statistics. Anthony Lyons �Appl. Res. Lab., PennState Univ., State College, PA 16804, [email protected]�

There has been, in general, a lack of quantitative comparison between high-frequency physics-based clutter model predictions andexperimental data due mainly to difficulties in performing well-controlled at-sea experiments and obtaining necessary ground truth. Toaddress this shortfall, experiments have been performed over the past 5 yrs to gather data with which to confront recently developedphysics-based clutter models. The experimental data sets were obtained during experiments conducted off of Elba Island, Italy in May2003 and at Seneca Lake, New York, in the summers of 2005 and 2006. Colocated high-frequency, broadband acoustic data and high-resolution environmental ground truth data were collected as part of these experiments. In all cases comparisons between model pre-dictions and measured data showed promising similarities in K-distribution shape parameter estimates and their dependence on band-width, grazing angle, and seafloor type. The favorable model/data comparisons show that it is possible to link the scattered envelopedistribution to measurable environmental properties, providing the foundation necessary for solving several important problems relatedto the detection of targets in non-Rayleigh clutter including performance prediction for different systems based on seafloor propertiesand extrapolation of performance to other systems and bandwidths.


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