Handout for PASS Presentation. NFPA Chicago

PASS Audibility Project Mustafa Z. Abbasi, Preston S. WilsonApplied Research LaboratoriesDepartment of Mechanical EngineeringThe University of Texas at AustinJoelle I. Suits, Ofodike A. EzekoyeDepartment of Mechanical EngineeringThe University of Texas at AustinCraig A. ChamplinDepartment of Communication Sciences and DisordersThe University of Texas at AustinCasey Grant Fire Protection Research Foundation

Mustafa Abbasi (UTexas Austin);Bob Athanas (FDNY);Chris Barron (SFFMA of Texas);Rob Bredahl (Austin FD);Keith Bryant (OK City FD);Mark Burdick (Glendale FD);DK Ezekoye (UTexas Austin);Casey Grant (FPRF);Zach Haase (NFPA ESE TC Task Group);Todd Keathley (Portland Fire & Rescue);Steve Lumry (OK City FD);Dennis McFadden (UTexas Austin);Bob Nicks (IAFF Local);Kris Overholt (UTexas Austin);Dan Rossos (Portland Fire & Rescue);Joelle Suits (UTexas Austin);Bruce Varner (NFPA ESE TC); andPreston Wilson (UTexas Austin)Fire Protection Research FoundationUniversity of TexasNew York FDAustin FDOklahoma City FDGlendale FDPortland Fire & RescueNFPA ESE TC Task GroupIAFF LocalState Firemen's & Fire Marshals' Association of TexasPanelOutline History and MotivationFireground sounds library Effect of gear on hearingSound in compartment firesFuture work

Brief History Firefighter disorientation is major problem From 1994 to 1998, an average of 725 fire fighters per year were caught or trapped in structure fires that resulted in injury or death of fire fighters*Firefighters can be overcome by heat or smoke of a fire and may be unable to alert other fire ground personnel to their need for assistancePASS device was standardized in NFPA 1982Significant improvements in testing and performance sinceNew features include automatic activation, integration in the radio and SCBA, etc.

*According to an analysis of National Fire Incident Reporting System (NFIRS) data by the National Fire Protection Association (NFPA)

4Shortfalls in PASS ?NIOSH reported that during the investigation of four fire fighter fatalities that occurred from 2001 to 2004, the PASS alarm signals were not heard or were barely audible.5

IntroductionSonar ApproachPassive sonar is used to detect, localize and classify underwater targets, in complicated environments, where optical means fail, by listening to the sounds they emit.

target radiating acoustic waves (sound)

IntroductionSonar ApproachPassive sonar is used to detect, localize and classify underwater targets, in complicated environments, where optical means fail, by listening to the sounds they emit.

multiple propagation paths

IntroductionSonar ApproachPassive sonar is used to detect, localize and classify underwater targets, in complicated environments, where optical means fail, by listening to the sounds they emit.

interaction with boundaries

IntroductionSonar ApproachPassive sonar is used to detect, localize and classify underwater targets, in complicated environments, where optical means fail, by listening to the sounds they emit.

potentially inhomogeneous medium (sound speed gradients)sound speeddepth

IntroductionSonar ApproachPassive sonar is used to detect, localize and classify underwater targets, in complicated environments, where optical means fail, by listening to the sounds they emit.

potentially inhomogeneous medium (flow)

IntroductionSonar ApproachPassive sonar is used to detect, localize and classify underwater targets, in complicated environments, where optical means fail, by listening to the sounds they emit.

potentially inhomogeneous medium (scattering objects)

IntroductionSonar ApproachTemperature gradient

Fire

Searching FirefighterMultiple PathsInteraction with BoundariesInhomogeneous Medium (Smoke)

source leveltransmission lossnoise leveldirectivity indexdetection threshold:signal-to-noise ratiorequired for operatorto detect signalsource-relatedenvironmentrelatedreceiver-relatedThe Sonar Equation

Sourceshttp://i.telegraph.co.uk/multimedia/archive/01565/living-room-fire_1565646i.jpghttps://si0.twimg.com/profile_images/2574267602/image.jpg

detecability thresholdPASS at 95 dB

Effect of 3 dB increase in PASS Signal

detecability thresholdPASS at 95 dB

Effect of 3 dB increase in PASS Signal

FF inside the contourcannot hear PASS

detecability thresholdPASS at 98 dBarea reduced by a factor of 2Effect of 3 dB increase in PASS Signal

detecability thresholdPASS at 105 dBarea reduced by a factor of 10Effect of 10 dB increase in PASS Signal

Fireground noiseThe fireground can be very noisyChainsaws, smoke alarms, fans, trucks, etc. Previous studies have focused on absolute sound pressure levels. No previous has measured the spectral content of fireground noiseOur current understanding of hearing shows that the level is the proper frequency is pertinent in regards to detection

Pictures of equipmenthttp://www.jarrodjones.com/wp-content/uploads/2013/03/500full.jpg

18Octave Band Analysis

Directionality

20Effect of GearHumans have learned to localize sound without wearing protective gearGear could reduce sound level heardHypotheses :Protective equipment is reducing the level firefighters hearGear could make it difficult to localize PASS location

ProcedurePurely physical measurementHelmets and other gear Acoustic Manikin (KEMAR)Anechoic chamberHead related transfer function

Human subject testingStandard hearing threshold measurementWith gear, without gearDiscrete frequencies, and one sample PASS

Example ResultsWith HelmetWithout Helmet

*Note the change in patterns

Overall Results : Helmets

24Helmet, Hood, Coat

Vs. = 3 dB Lower

Vs. = 1 dB LowerBare Bare Helmet, hoodand coatHelmet only25Manikin Testing ConclusionsSignificant difference amongst helmetsThe helmets change the physical patterns heard by the firefighters.The could affect localizing the PASS Average 3 dB level SPL drop with gearMaybe increase PASS levels to compensateHuman TestingManikin tests showed 3 dB lower level caused by helmet and gearHuman subject testing was conducted to test this observationStandard method of limits with adaptive one up one down rules.Test were performed with subject wearing :No PPVHelmet Helmet, NOMEX hood, coat 6 subjects tested so far 27ProcedurePlayback signalSubject indicates if they heard the signalOperator turns the level down or up in correlation with the subjects response

28Subject Test Results

++1. http://www.rumfordfire.com/Fire/helmet.gif2. http://a248.e.akamai.net/origin-cdn.volusion.com/fjrx4.tvu4w/v/vspfiles/photos/MJpacIIPBIG-2.jpg?13593693363. http://www2.dupont.com/Media_Center/en_US/assets/images/releases/nr_photo_FS_Turnout_Coat.jpg29Human Testing ConclusionsStrongest effect shown by the helmetIncreased auditory threshold Lower SNR, lower possibility of detectionPASS Audibility ProjectFuture Field Testing with Fire Service PartnersSimulate real fire noise using recordings, and have firefighters locate the PASS.Need help from partners to identify structures that can be used for tests.

32Effect of Fire on PASSExperimental MeasurementComputer modeling

IgnitionExtinction

Free Field PASS Signal

10 second into the fireQuestionsHumans dont hear all frequencies equallyMost sensitive between 1-3 kHz with normal hearing

Standard weighting curves mimic how we hearA weighting most commonly usedAside on Hearing (Loudness)

http://en.wikipedia.org/wiki/LoudnessFind cyrves in paper. 35