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Today’s hearing aids: Using technology to its best potential

Susan Scollie, Ph.D.Associate Professor

Child Amplification Laboratory

School of Communication Sciences and Disorders

National Centre for Audiology

University of Western Ontario

Best practices in 2013

Hearing aids with modern DSP, follow up

Highly adjustable frequency response

Multiple memories and signal processing options.

Many families choose early hearing aid fittings

RECD and routine use of electroacoustic analysis

Prescriptive Method (e.g. DSL5)

EHDI allows early identification

Ear specific electrophysiological hearing estimate in the first

months of life

Parent support and family centred choice of

communication development

Clear areas of agreement:� Frequency specific stimuli for electrophysiologic hearing estimates are preferred to broadband stimuli◦ Frequency specific ABR and ASSR

� Normed corrections from nHL to eHLfacilitate the transfer of these data to hearing aid prescription.◦ Missing this step may lead to overamplification.

� Measuring the RECD is an accepted method for estimating the child’s ear canal acoustics and for tracking this as the child grows.◦ All pediatric prescriptions now include the RECD.

A few favorite resources:� Online:◦ http://www.audiologyonline.com/audiology-ceus/course/fitting-hearing-aids-to-babies-

17201

◦ http://www.audiologyonline.com/articles/article_detail.asp?article_id=2063

◦ http://www.audiologyonline.com/interview/interview_detail.asp?interview_id=442

◦ http://www.audiologyonline.com/articles/20q-baby-steps-following-verification-783

� Textbook:◦ Seewald & Tharpe: Comprehensive Handbook of Pediatric Audiology

� ASHA Division 9:◦ Scollie, S. (2010). Hearing aid signal processing for children: When and how

to use it. ASHA Division 9: Perspectives on Hearing and Hearing Disorders in Childhood, 20(2), 38-75.

� Protocols online:◦ http://hearing.screening.nhs.uk/audiologyprotocols

◦ http://www.phsa.ca/AgenciesAndServices/Services/BCEarlyHearing/ForProfessionals/Resources/default.htm

The bottom line:

� Pediatric audiologists work pretty hard to provide:◦ A physically comfortable hearing aid with acceptable, comfortably clear sound quality that allows a child access to as many sounds of speech possible, across as many input levels as possible.

How about these features?

� Feedback control

� Venting

� Digital noise reduction

� Frequency lowering

For each of these, we can review the evidence, consider developmental impacts and needs, and plan for fitting & verification.

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Topic One: Feedback controlAge group Clinical need Evidence Fitting &

verification

Infants Maximum: the rapidly growing ear presents an ongoing challenge.

Devices vary in terms of the gain limitations imposed by the feedback control system.

Measuring the hearing aid’s response before, during, and after may revealimportant information.

Young children High: ear growth slows but earmoldshrinkage may be a factor. When should venting be introduced?

Older children and adults

Possible: Depending upon gain and venting. When should venting be introduced?

Topic Two: VentingAge group Clinical need Evidence Fitting &

verification

Infants Even when “needed”, it is very difficult to attain (ear size).

Is the ear large enough?

Is the feedback control system effective enough to support the venting?

What are the benefits of venting?

Real ear measurement techniques for ventingevaluation.

Children Large incidence of children with near-normal hearing in the low frequencies. When should venting be introduced?

Let’s merge those into one topic:

The fitting!

The vent

The aided response

The feedback control

Is the vent providing any vent-transmitted sound?

Open ear:

Acoustically transparent to

1000 Hz.

Is the feedback controller effective?Combine vent transmitted sound with the hearing aid’s electroacoustic response:

� In the low frequencies:◦ Normal pitch cues, binaural cues for localization (interaural time differences) from the normal acoustic path.

� In the high frequencies:◦ Electroacoustic gain to provide access to consonants.

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Evidence considerations:

Adults Kids

(Noble et al 1998) (Johnstone et al 2010 , 2011)

With closed versus open ears/molds, people had more difficulty with accurate horozontal

localization.

Evidence considerations:

Adults Kids

(Noble et al 1998) (Johnstone et al 2010, 2011)With an open fitting, this earlier-fitted child with unilateral hearing loss

performed better than with a more occluding fitting (or unaided).

Later-fitted children performed more poorly.

Venting & feedback:

� Not the challenge it used to be.

◦ Feedback control systems have advanced, allowing more venting than ever before. But: they also vary. Can you use your verification system to learn which ones are best?

� In pediatrics, have we lost sight of venting in the face of more complex dsp? Or perhaps in the face of such tiny ear canals? I know this is a back to basics message, but:

◦ Does Johnstone raise an important point? Is early venting better than late venting?

Topic Three: Noise reductionAge group Clinical need Evidence Fitting &

verification

Infants Possible: Less need at home, car noise? Shopping centres? Daycare?

Noise levels in schools and daycares.

Children’s variations in loudness, preference for environment-specific choices.

New DNR studies on kids provide helpful information.

Does the hearing aid preserve speech audibility in the noise program?

Who switches?

How much noise reduction does the DNR provide?

Young children Probable: Daycare, car, transitioning to school

Older children and adults

Probably:Noise levels in schools, importance of multi-environmental functionality.

Noise levels at daycare & school:

Crukley, Scollie, & Parsa 2011

Options for noise management:

� A noise program with less gain?◦ An older trial of NAL-NL1 vs. DSL4 showed that many school aged kids liked having and used two programs. They often chose programs based on the sound levels and noisiness of the environment. (Scollie et al, 2010)

� Digital noise reduction?◦ Newer evidence reveals that DNR may ease the burden of listening in noise for children, with older children more able to derive this benefit. No harms noted. (Pittman, 2011, Stelmachowicz et al, 2010)

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Is the DNR effective? A target for use in noise programs?

� The DSL5 prescription includes a “noise program target” with slightly less gain. (Scollie et al, 2005)

� In a recent evaluation, this prescription maintained speech recognition, while reducing loudness for high level signals.

Crukley, & Scollie, 2012

Frequency response changes Consonant recognition scores

A target for use in noise programs?

Loudness ratings

Crukley, & Scollie, 2012

Noise programs:

� It’s not only about the DNR.◦ We may be able to have a systematic approach to fitting the gain in noise programs, if one goal is to maintain good speech audibility for mid to high level speech.

◦ Should we couple this to DNR? To directionality?

� What about verification measures?◦ Can we use these techniques to compare strengths or products?

◦ How much DNR is enough?

Validation measures?

� Interested in knowing if young children are benefitting in quiet and noisy environments?

� A clinical monitoring protocol:� Bagatto, M. P., Moodie, S. T., Malandrino, A. C., Richert, F. M., Clench, D., & Scollie, S. D. (2011). The University of Western Ontario Pediatric AudiologicalMonitoring Protocol (UWO PedAMP). Trends in Amplification, 15(1), 57-76.

Topic Three: Frequency loweringAge group Clinical need Evidence Fitting &

verification

Pediatrics Possible: If the hearing aid bandwidthrestricts access to some speech sounds.

Adult-child differences in the need/benefitassociated with both bandwidth and frequency compression.

Adult-child differences in response to sound quality.

Pediatric evidence for acclimatization, benefit.

Systematic fitting approaches exist.

Systematicrelationships exist between strength of setting, sound quality, and benefit.

New validation tools allow outcome assessment.

Adults Possible: If the hearing aid bandwidthrestricts access to some speech sounds. Some wonder if adults are as able to become accustomed to it.

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Frequency Lowering (FL): three types

� Frequency Compression (FC)

◦ Phonak SoundRecover®

◦ Siemens FC

� Frequency Transposition (FT)

◦ WidexAudibilityExtender ®

� Frequency translation◦ Starkey Spectral IQ ®

Frequency (Hz)

Below cutoffAbove cutoff

Frequency (Hz)

Below cutoffAbove cutoff

Frequency (Hz)

Below cutoffAbove cutoff

Frequency Lowering (FL): three types

Frequency (Hz)

Below cutoff

Frequency (Hz)

Below cutoff

Frequency (Hz)

Below cutoffAbove cutoff

� Frequency Compression (FC)

◦ Phonak SoundRecover®

◦ Siemens FC

� Frequency Transposition (FT)

◦ WidexAudibilityExtender ®

� Frequency translation◦ Starkey Spectral IQ ®

Fitting tips:

� Start with the best possible fit without FL.◦ Why?

� Examine the fitting for mid-level speech at 65 dB SPL to determine what is missing.◦ Probe further using frequency-specific sounds

◦ We’ll talk about clinical options for this.

� Important: if the frequency lowered signal is far below threshold, it will not help.

� Important: if the frequency compression is too strong, it may affect sound quality.

Fitting tips:

� Make both S and SH audible if possible.

� Separate them in frequency and in level to mimic the natural cues that allow listeners to hear that these are two different sounds.

� Use the weakest possible setting that provides these effects.

� An acclimatization period may be necessary to obtain maximum benefit.

� Lack of benefit is very likely when the frequency-lowered signal is inaudible.

Outcomes in adults and children:

� 24 patients: 11 children and 13 adults

◦ Phonak frequency compression (pre-commercial, ear level devices)

� Most of the children were followed for about 2 years. (2009b) Glista et al (2009a), IJA, (2009b)

Hearing ReviewSupport: NSERC-CIHR CHRP, Hearing Foundation of Canada, Phonak AG

Speech sound detection improved.

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Consonant & word-final plural recognition improved.

Individual adults, sorted by HL:

Individual kids, sorted by HL: Audiometric & age candidacy.

� Significant predictors of outcome:◦ Age group (adult versus child)

◦ Better ear high frequency pure tone average

◦ The lowest frequency at which the audiogram had a severe loss (drop off frequency)

Sound quality of female speech:

(Parsa et al, in press)

Time course of acclimatization.

� 6 participants (11-18 years)◦ DSL5 at baseline trial

◦ Frequency compression trial

◦ Withdrawal and testing

◦ Four month trial, no training.

� Some participants had significant acclimatization trends. May relate to degree of hearing loss?

Glista, Scollie, and Sulkers (2012, JSLHR)

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Time course of acclimatization(Glista et al, 2012, JSLHR, 55(6))

Fitting and baseline testing

Testing with FC

- Every 2 to 4 weeks for several months

Testing after withdrawal of

FC

Aided cortical potentials:

Glista et al (2012): http://www.hindawi.com/journals/ijol/2012/982894/

Acclimatization summary:

� Some but not all listeners!

� Some show gradual improvement, others a sudden jump after 6-8 weeks.

� Improvement on the day of fitting is not always the case.

� Results of verification generally agree with behavioural outcomes.

Fitting & verification

� A new test signal from the Verifit allows us to see if a high frequency band is lowered.

� Run with & without SoundRecover.

� Test at 3.1, 4k, 5k or 6.3kHz.

� May offer a calibrated alternative to live voice /s/ and /sh/.

Is the frequency lowering tuned?

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Real Example: Tuning

Scollie & Glista (2011) ENT & Audiology News

And the winner is…

Test

Percent

Correct

Score

Setting 1

Percent

Correct

Score

Setting 2

Interpretation

Nonsense syllables 56% 69%Significant improvement with the

revised setting

Discrimination of S/SH 37% 65%Significant improvement with the

revised setting

Interpret?

S

Sh

Frequency lowering off:

SH

S

Frequency lowering A:

SH

S

Frequency lowering B:

SH S

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Frequency lowering C:

SH

S

Fitting frequency lowering:

� The hearing aid’s gain and FC interact:

◦ If you have less high frequency gain, you will need to use a stronger FC setting to make S audible.

◦ FC strength is correlated with sound quality changes… use the weakest setting you can that has positive effects.

◦ Fine tuning is possible.

◦ Verification and real ear measurement is possible.

Fitting frequency lowering:

� Is the need for frequency lowering different in these scenarios?

◦ An adult with a severe high frequency hearing loss versus a child with the same loss?

◦ An older child with a moderately severe loss and a conventional fitting versus a power receiver in the ear with a custom concha mold.

� Verification measures can help us to assess the latter situation.

� Performance measures may help in either case.

“For Monday Morning”

� Have a look at the verification article (Glista & Scollie, 2009, AudiologyOnline) and give it a try!

◦ It shows speech bands and live s - sh.

◦ Same principles as discussed today.

Validation measures?

� Interested in knowing if people can hear new sounds with frequency lowering?

� Interested in knowing if your extended bandwidth fittings are providing access to /s/ without frequency lowering?

� New clinical test:� Glista, D. and Scollie, S. (2012). Development and Evaluation of an English Language Measure of Detection of Word-Final Plurality Markers: The University of Western Ontario Plurals Test. American Journal of Audiology, 21: 76-81.

Colleagues and support

� Thanks to the Mayo Clinic for this opportunity!

� My deepest appreciation to my former Ph.D. students whose wonderful work was shared here: Danielle Glista, Ph.D., Marlene Bagatto, Ph.D., Jeff Crukley, Ph.D.

� Lab members and NCA Colleagues:◦ Vijay Parsa, Sheila Moodie, Richard Seewald

◦ Past students: Andrea Dunn, Melissa Polonenko, Jacob Sulkers, Julie Seto

◦ Current students: Viji Easwar, Kelley Keene

� Research Funding and Collaboration: PhonakAG, Ontario Research Fund. Past support from Mason’s Foundation of Ontario, CIHR, and NSERC.

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Selected ReferencesCrukley, J., and Scollie, S. (2012). Children’s Speech Recognition and Loudness Perception with the

Desired Sensation Level v5 Quiet and Noise Prescriptions. American Journal of Audiology Doi: 10.1044/1059-0889(2012/12-002).

Crukley, J., Scollie, S. , & Parsa, V. (2011). An exploration of non-quiet listening at school. Journal of Educational Audiology, Vol 17,, 23-35.

Glista, D., Easwar, V., Purcell, D., and Scollie, S. (2012). A Pilot Study on Cortical Auditory Evoked Potentials (CAEPs) in Children: Aided CAEPs change with Frequency Compression Hearing Aid Technology, International Journal of Otolaryngology.

Glista, D., & Scollie, S. (November, 2009). Modified Verification Approaches for Frequency Lowering Devices. Audiology Online, 1-11. Retrieved from http://www.audiologyonline.com/articles/article_detail.asp?article_id=2301

Glista, D. and Scollie, S. (2012). Development and Evaluation of an English Language Measure of Detection of Word-Final Plurality Markers: The University of Western Ontario Plurals Test. American Journal of Audiology, 21: 76-81.

Glista, D., Scollie, S., Bagatto, M., Seewald, R., Parsa, V., & Johnson, A. (2009). Evaluation of nonlinear frequency compression: Clinical outcomes. International Journal of Audiology, 48(9), 632-644.

Glista, D., Scollie, S., & Sulkers, J. (2012). Perceptual Acclimatization Post Nonlinear Frequency Compression Hearing Aid Fitting in Older Children. JLSHR, 55(6): 1765-1787.

Pittman, A. (2011). Children’s performance in complex listening conditions: Effects of hearing loss and digital noise reduction. Journal of Speech Language and Hearing Research, 54(4), 1224-1239.

Scollie, S. (2010). Hearing aid signal processing for children: When and how to use it. ASHA Division 9: Perspectives on Hearing and Hearing Disorders in Childhood, 20(2), 38-75.

Wolfe, J., John, A., Schafer, E., Nyffeler, M., Boretzki, M., & Caraway, T. (2010). Evaluation of non-linear frequency compression for school-age children with moderate to moderately-severe hearing loss. Journal of the American Academy of Audiology, 21(10), 618-628.