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Mild Hearing Loss is Serious Business. Harvey Dillon Sharon Cameron, Teresa Ching, Helen Glyde, Gitte Keidser, David Hartley, Jorge Mejia NAL, The Hearing CRC IHCON, 2010. Slides on the NAL web site: www.nal.gov.au. What is mild hearing loss?.

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Mild hearing loss is serious business l.jpg

Mild Hearing Loss is Serious Business

Harvey Dillon

Sharon Cameron, Teresa Ching, Helen Glyde, Gitte Keidser, David Hartley, Jorge Mejia

NAL, The Hearing CRC

IHCON, 2010



What is mild hearing loss l.jpg
What is mild hearing loss?

  • Four-frequency average (500, 1000, 2000, 4000 Hz) hearing loss in better ear between 20 and 40 dB HL

  • Self-reported disability or handicap within a certain range

  • SRT in noise loss of between 3 and 6 dB




How prevalent is mild hearing loss6 l.jpg
How prevalent is mild hearing loss?

  • Davis (1995): 16% of adult population

  • Wilson (1990): 18% of adult population

  • Hartley et al (in press): 34% of people aged > 50 years


Blue mountains 4fahl better ear l.jpg
Blue Mountains 4FAHL better ear

Hartley et al (in press)




Mild losses for study l.jpg
Mild losses for study

~ Minimum loss eligible for government benefits

Mild loss (4FA=29 dB)

Mild-mod loss (4FA=39 dB)

~ Median loss newly fitted in Australia


Mild losses for study12 l.jpg
Mild losses for study

4FA HL

Mild 9 dB

Mild-mod 39 dB

Moderate 49 dB

Mod-Sev 59 dB

Severe 69 dB



Penetration by hearing loss l.jpg
Penetration by hearing loss hearing loss?

  • Penetration as a function of hearing loss

    • Davis (1995)

    • Wilson et al (1998)

    • Hartley et al (in Press)

    • Kochkin

consistent


Aid ownership by hearing loss blue mountains population 55 years l.jpg
Aid ownership by hearing loss hearing loss?Blue Mountains Population >55 years

Hartley et al (in Press)



Characteristics of mild loss l.jpg
Characteristics of mild loss hearing loss?

  • Threshold elevation √

  • Loss of OHC/OAE

  • Loss of frequency resolution – TEN, PTC, FRI

  • Loss of temporal (envelope) resolution

  • Loss of fine temporal information

  • Loss of spatial processing

  • Loss of SRT in noise

  • Increased disability and handicap


Loss of active process in cochlear ohc and oae l.jpg
Loss of active process in cochlear: hearing loss?OHC and OAE


Loss of frequency resolution l.jpg

FRI hearing loss?

A

A

f

f

Ching & Dillon (unpublished data)

Loss of frequency resolution


Frequency resolution l.jpg
Frequency resolution hearing loss?


Loss of temporal resolution l.jpg

A hearing loss?

TRI

t

t

Loss of temporal resolution


Temporal resolution l.jpg
Temporal resolution hearing loss?

Ching & Dillon (unpublished data)


Loss of fine temporal information l.jpg
Loss of fine temporal information hearing loss?

  • 20 synapses per IHC

  • Synapse loss or IHC loss  reduced averaging  temporal jitter

Inspiration:

  • Bodian, Lieberman, Moore, Pichora-Fuller, Spoendlin,



Spatial processing disorder l.jpg
Spatial Processing Disorder hearing loss?

Speech

Sharon Cameron

Noise

Noise

Noise

Noise

26


Listening in spatialised noise sentences lisn s conditions l.jpg
Listening in Spatialised Noise - Sentences hearing loss?(LiSN-S) Conditions

Total Advantage

Talker Advantage

Spatial Advantage

Same voices

Different voices

Same

direction

Low Cue

Different

directions

High Cue

Cameron & Dillon (2009)



Spatial advantage spatial release from masking l.jpg
Spatial Advantage hearing loss?(≡ Spatial Release from Masking)

Nth America

Australia

Better


Spatial advantage l.jpg
Spatial Advantage hearing loss?

Better



Spatial processing remediation pre vs post n 9 l.jpg
Spatial processing remediation hearing loss?Pre vs. Post (n=9)

LC SRT - p = 0.158

Talker Advantage - p = 0.981

HC SRT - p = 0.0002

Spatial Advantage - p = 0.0002

Total Advantage - p = 0.001



Spatial hearing loss in hearing impaired people lisn s prescribed gain amplifier l.jpg
Spatial hearing loss in hearing-impaired people: hearing loss?LiSN-S Prescribed Gain Amplifier


Deficit in srt n with hearing loss l.jpg
Deficit in SRT hearing loss?n with hearing loss

R = -0.87

P = 0.000006

Cameron, Glyde & Dillon, unpublished data)


Cause of deficit in srt n l.jpg
Cause of deficit in SRT hearing loss?n

R = -0.86

P = 0.00001

Cameron, Glyde & Dillon, unpublished data)


Talker advantage deficit versus age l.jpg
Talker advantage deficit versus age hearing loss?

Cameron, Glyde & Dillon, unpublished data)


Binaural processing l.jpg

ILD hearing loss?

ITD

SO / IC / A1

~

Sensorineural

hearing loss

CN

CN

Binaural processing

Executive

control

CAPD

x

x

ILD

ITD

R

L


Loss of snr in understanding speech l.jpg
Loss of SNR in understanding speech hearing loss?

“Basic” loss of 0.6 dB per 10 dB of loss

+

Loss of Spatial release from masking of 2.3 dB per 10 dB of loss

+

Loss of Talker cue release from masking of 0.5 dB per 10 years of age


Loss of srt in noise l.jpg

1 dB / 10 dB hearing loss?

1.8 dB / 10 dB

Loss of SRT in noise

Commonly 1.5 dB increase in SNR per 10 dB of hearing loss

SNR = -4 dB

Carter, Zhou & Dillon, unpublished data)



Speech and noise levels l.jpg

SNR hearing loss?

Speech and noise levels

Source: Pearsons, Bennett and Fidell (1977)


Calculation of sii l.jpg
Calculation of SII hearing loss?

Noise = 60 dBA Speech = 64 dBA SIInh=0.65 SIIhi=0.46


Effective audibility l.jpg

20 hearing loss?

40

60

80

100

Effective audibility


Transfer function sii percent correct l.jpg
Transfer function hearing loss?SII  Percent correct


Mild losses for study45 l.jpg
Mild losses for study hearing loss?

Mild loss (4FA=29 dB)

Mild-mod loss (4FA=39 dB)


Predicted speech intelligibility l.jpg
Predicted speech intelligibility hearing loss?

Greatest problems in noisy places !!


Predicted variation of srt n with hearing loss l.jpg
Predicted variation of SRT hearing loss?n with hearing loss

Modified SII model predicts only 0.4 dB loss per 10 dB of hearing loss

Speech

level


Modification of sii l.jpg
Modification of SII hearing loss?

  • Assume normal hearers get 6 dB advantage from spatial separation of speech and noise

  • Assume hearing impaired listeners lose spatial advantage at a rate of 1.3 dB per 10 dB of loss (above SII predictions)

     total loss of SNR is 1.7 dB per 10 dB of loss


Calculation of intelligibility l.jpg
Calculation of intelligibility hearing loss?

Speech spectrum

Sensation Level

Effective audibility

Noise spectrum

SII

(Information received)

Percent correct

Max

Importance function

Threshold


Do hearing aids help people with mild hearing loss l.jpg

current hearing loss?

^

Do hearing aids help people with mild hearing loss?


Benefit of hearing aids l.jpg
Benefit of hearing aids hearing loss?

Predict increase in speech intelligibility

with

the modified Speech Intelligibility Index


Calculation of aided benefit l.jpg
Calculation of aided benefit hearing loss?

Noise = 50 dBA

Speech = 58 dBA


Speech intelligibility mild loss l.jpg
Speech intelligibility hearing loss?(mild loss)

  • Hearing aid “helps” in quiet places

  • Tiny additional benefit from directivity

Conditions:

DI = 3 dB when REIG > 3 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -3.7 dB


Speech intelligibility mild moderate loss l.jpg
Speech intelligibility hearing loss?(mild-moderate loss)

  • Hearing aid “helps” in quiet places

  • Tiny additional benefit from directivity

Conditions:

DI = 3 dB when REIG > 3 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -5.1 dB


Speech intelligibility moderate loss l.jpg
Speech intelligibility hearing loss?(moderate loss)

Conditions:

DI = 3 dB when REIG > 3 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -6.5 dB


Speech intelligibility moderate severe loss l.jpg
Speech intelligibility hearing loss?(moderate-severe loss)

Conditions:

DI = 3 dB when REIG > 3 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -7.7 dB


Speech intelligibility severe loss l.jpg
Speech intelligibility hearing loss?(severe loss)

Conditions:

DI = 3 dB when REIG > 3 dB

n.h. spatial adv = 6 dB

∆SNR loss re n.h. = -9 dB


Summary of benefit versus hl l.jpg
Summary of benefit versus HL hearing loss?

Background noise level

40 dB A

60 dB A

80 dB A


Why don t directional microphones help more in noise l.jpg

Why don’t directional microphones help more in noise? hearing loss?

(and adaptive noise reduction)


1 impact of open fittings on directivity l.jpg
1. Impact of open fittings on directivity hearing loss?

Directional

Omni-directional

DI = 3 dB  1.5 dB

DI = 10 dB  5 dB


Frequency range of directional mic mild loss l.jpg

50 hearing loss?

60

70

80

Frequency range of directional mic (mild loss)

Effect of dynamic noise reduction on directional mic


Effect of aiding at 60 dba mild loss l.jpg
Effect of aiding at 60 dBA hearing loss?(mild loss)

Noise = 60 dBA

Speech = 64 dBA


Effect of aiding at 80 dba mild loss l.jpg
Effect of aiding at 80 dBA hearing loss?(mild loss)

Noise = 80 dBA

Speech = 76 dBA


2 impact of reverberation on directivity and vice versa l.jpg
2. Impact of reverberation on directivity hearing loss?(and vice versa)

Total

Reverberant

Direct


Slide65 l.jpg

Total

Direct

Reverberant


Benefit of directional microphones l.jpg
Benefit of directional microphones hearing loss?

Benefit affected by:

  • Directivity pattern of microphone

  • Distance and direction of talker and noise sources

  • Acoustics of the room

  • Frequency range over which the hearing aid is directional

  • Frequency range over which the wearable has usable hearing

  • Nothing else

(OK, Measurement error!!)


Conclusion of acoustic analysis l.jpg
Conclusion of acoustic analysis hearing loss?

  • People with mild loss need help in noisy places

  • Hearing aids increase the speech information available mostly in quiet places!

  • Mics directional only where there is gain

    • high frequencies and lower levels

    • Where audibility is limited by threshold, not noise


Slide68 l.jpg

So, objective benefit questionable, and increasing with degree of loss, but …….

What do hearing aid users say ?


Experimental evaluation of self reported benefit l.jpg
Experimental evaluation of self-reported benefit degree of loss, but …….

  • 400 clients sampled from national database

    • 41,521 new clients fitted Feb to Sept, 2004

  • Audiometric and other details obtained from clients’ files

  • Questionnaire sent to clients 5 to 12 months after fitting

    • International Outcome Inventory for Hearing Aids

    • Plus 6 purpose-designed questions

  • Non-responders followed up by phone or additional mail to get a high response rate (effectively 86%)


Hearing loss distribution l.jpg
Hearing loss distribution degree of loss, but …….

Sample distribution

Population distribution


Usage of hearing aids l.jpg
Usage of hearing aids degree of loss, but …….


Factor analysis of questionnaire l.jpg

Composite benefit degree of loss, but …….

Composite difficulty

Vision

Factor analysis of questionnaire

International Outcomes Inventory

for

Hearing Aids


Effect of hearing loss on benefit l.jpg
Effect of hearing loss on benefit degree of loss, but …….



W ishes a nd n eeds t ool l.jpg
W degree of loss, but ……. ishes And Needs Tool

  • How strongly did you want to get hearing aids?

     Wanted it very much

     Wanted it quite a lot

     Wanted it moderately

     Wanted it slightly

     Did not want it

  • Overall how much difficulty do you have hearing when you are not wearing your hearing aids?

     Very much difficulty

    Quite a lot of difficulty

    Moderate difficulty

     Slight difficulty

    No difficulty


Difficulty hearing unaided and wish to get hearing aids l.jpg

Very much degree of loss, but …….

Not at all

Want hearing aids

Difficulty hearing unaided and wish to get hearing aids

Unaided difficulty related to wish to get hearing aids


Need increases with hearing loss l.jpg
Need increases with hearing loss degree of loss, but …….


Benefit versus need strength l.jpg
Benefit versus need strength degree of loss, but …….



Factors affecting benefit experienced and hence the reports of others l.jpg
Factors affecting benefit experienced hearing aids?(and hence the reports of others)

  • Degree of pure-tone loss

  • Self-reported disability and handicap

  • Acceptable Noise Level

  • Stigma / cosmetic concern

  • Manipulation and management

  • Age

  • Tinnitus

  • Personality ….


Personality l.jpg
Personality hearing aids?

People more likely to acquire hearing aids are:

  • Open

  • Non-obsessive

  • Non-neurotic

  • Internal locus of control

    People more likely to report benefit are:

  • Extroverted

  • Agreeable


Health belief model l.jpg
Health Belief Model hearing aids?

People act rationally, in their best interests, based on their beliefs

Weighing up of beliefs for and against a health decision

Do I have

a problem?

Is it serious

enough for me to

want to remove it?

Is there a

solution

that works?

Disadvantages

Advantages

What are the

disadvantages

of the solution?

“My hearing loss is not bad enough to need them” (Kochkin, 1993)


Motivation comes from l.jpg

Self-image hearing aids?

Expect benefit

Try them

Expect to manage them

$ Cost OK

Motivation comes from ….

Acknowledge loss

Experience difficulty

Experience handicap


Health belief model84 l.jpg
Health belief model hearing aids?

Difficulties experienced: frequency, severity

Self-image

Hearing aid

effectiveness

External

image

Ability to

manage

Hearing

loss

Cost

Incon-venience


Health belief model85 l.jpg

Self-image hearing aids?

External

image

Hearing aid

effectiveness

Ability to

manage

Difficulties experienced: frequency, severity

Cost

Inconven-ience

Hearing

loss

Health belief model


Health belief model86 l.jpg

Difficulties experienced: frequency, severity hearing aids?

Self-image

Hearing aid

effectiveness

External

image

Ability to

manage

Hearing

loss

Cost

Inconven-ience

Health belief model



Improving advantages and removing disadvantages l.jpg

Cost improved?

Working better

in noise

Improving advantages and removing disadvantages

  • WDRC

  • Slim-tube, miniaturization

  • Feedback cancellation

  • Low-level expansion

  • Re-chargeable batteries

  • Auto telecoil

  • Frequency lowering

  • Bandwidth extension

  • Trainable responses

  • Adaptive noise reduction

  • Transient noise reduction

  • Directional microphones

Problem 1

Solution 1

Problem 2

Solution 2

Problem 3

Solution 3



Binaural processing super directional microphone mejia et al 2007 l.jpg
Binaural-Processing Super-directional Microphone improved?(Mejia et al., 2007)

Rear- directional array

W1

W2

Q1

Q2

Binaural beamformer

Q3

Q4

W3

W4

Masking threshold

Main directional signal

d = 3 ms delay

(Precedence effect)

K

K

Subsidiary signal

Z-d

HRTFL

HRTFR

Cross-fading process

DOA- reconstruction

Lout

Rout

Outputs with spatial reconstruction



Speech reception threshold in noise reverberant room crit dist 0 4m radius 1 m l.jpg
Speech reception threshold in noise improved?Reverberant room: crit dist = 0.4m, radius = 1 m

Mejia and Johnson, unpublished data


Slide93 l.jpg

Linked binaural hearing aid technology improved?

Female

talker

Male

talker

Listener

Children

playing

Hearing Aid


Blind source separation binaural noise reduction l.jpg
Blind-source separation binaural noise reduction improved?

h.i.

gain most from directivity

n.h. benefit from re-insertion of spatial cues

Implication: People with mild or moderate hearing loss were not making much use of spatial cues.


Effect of super directivity mild loss l.jpg
Effect of super-directivity improved?(mild loss)

  • Super-directional mic not directional at all over a broader and broader range as noise levels rise

Conditions:

DI = 6 dB when REIG > 3 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -3.7 dB




Effect of low frequency directivity mild loss l.jpg
Effect of low-frequency directivity improved?(mild loss)

  • Now directional over entire frequency range in noisy places

Conditions:

DI = 3 dB when REIG ≥ 0 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -3.7 dB


Occlusion with closed molds l.jpg
Occlusion with closed molds improved?

Vent or leak transmission in


Active occlusion reduction l.jpg
Active Occlusion Reduction improved?

Hear

Aid

C

+

Σ

-

A

B


Active occlusion reduction101 l.jpg
Active occlusion reduction improved?

Mejia, Dillon, & Fisher (2008)


In combination l.jpg
In combination? improved?

Active occlusion reduction

(closed mold)

Super-directivity

+

= ?


Low frequency super directivity mild loss l.jpg
Low-frequency super-directivity improved?(mild loss)

  • Super-directivity over entire frequency range

  •  super-normal hearing

Conditions:

DI = 6 dB when REIG ≥ 0 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -3.7 dB


Low frequency super directivity mild moderate loss l.jpg
Low-frequency super-directivity improved?(mild-moderate loss)

  • Super-normal hearing for the median hearing aid wearer

Conditions:

DI = 6 dB when REIG ≥ 0 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -5.1 dB


Low frequency super directivity moderate loss 4fa 49 8 db hl l.jpg
Low-frequency super-directivity improved?(moderate loss, 4FA = 49.8 dB HL)

  • Super-normal hearing in very noisy places for even a moderate-severe loss

Conditions:

DI = 6 dB when REIG ≥ 0 dB

n.h. spatial adv = 6 dB

∆SNR re n.h. = -6.5 dB


Adaptive noise reduction l.jpg
Adaptive noise reduction improved?

  • Gain dependent on SNR correct in principle, but room for improvement:

    • Gain reduction can reduce directional mic effectiveness

    • No point in reducing noise below threshold

    • Gain increase where SNR is best is just as important


Slide107 l.jpg
Cost improved?

Jump to summary


Self fitting hearing aid l.jpg
Self-fitting hearing aid improved?

NAL-NL2 Prescription Formula

Real-ear to coupler difference

Automatic

Adjust Hearing Aid

Audiometer

Plus trainability

Australia, USA: 1 audiologist per 10,000 people

Developing countries: 1 audiologist per 500,000 people, to 1 per 6,000,000



Test retest standard deviations l.jpg
Test-retest standard deviations improved?

RECD

Auto Aud

Adjust

NAL-NL2

Manual audiometry (5 dB Hughson-Westlake)

Automatic audiometry (2 dB final step size)


Real ear to dial difference inter subject standard deviations l.jpg
Real-Ear to Dial Difference: improved?Inter-subject standard deviations


Real ear to dial difference inter subject standard deviations112 l.jpg
Real-Ear to Dial Difference: improved?Inter-subject standard deviations

Insert

Saunders & Morgan

Valente et al

Hawkins et al

Supra-aural

Valente et al

Hawkins etal


Trainable hearing aids l.jpg

CR improved?

Gain

CT

Trainable Hearing Aids


In summary l.jpg

In summary… improved?


In summary115 l.jpg
In summary improved?

very

How prevalent is mild hearing loss?

How common is hearing aid use amongst those with mild hearing loss?

not very

many, including spatial hearing loss

What are the characteristics of mild hearing loss?

Is mild hearing loss a problem to people?

yes, in noise

Do hearing aids help people with mild hearing loss?

only in quiet places

….. expected benefit too small re need

Why don’t more people with mild hearing loss even try hearing aids?

closed-ear, binaural processing

How can hearing aids provide greater benefit where it is most needed?


Messages for l.jpg
Messages for …. improved?

  • Public health authorities:

    • Increase hearing awareness (prevention, rehabilitation)

    • Increase hearing screening opportunities


Messages for117 l.jpg

  • Clinicians: improved?

    • Discern primary reasons why unmotivated clients are unmotivated

    • Provide information to change unrealistic beliefs

    • Understand and diagnose the fundamental problem that clients are presenting with SRT loss

Messages for ….


Messages for118 l.jpg
Messages for …. improved?

  • Researchers:

    • Better understanding of the components and causes of SNR loss

    • Prescription procedures for adaptive noise suppression

      • Time constants

      • Relationship with thresholds

      • Relationship with noise spectrum and level


Messages for119 l.jpg
Messages for …. improved?

  • Manufacturers:

    • Achieve better performance in noise

      •  Binaural processing

      •  Closed fittings

      •  Wireless

      •  Smarter adaptive noise suppression


Hearing aids of the future l.jpg
Hearing aids of the future improved?

?

  • Convergence:

  • hearing aid/enhancer,

  • phone interface,

  • hearing protector,

  • computer interface (in and out),

  • music player,

  • GPS interface


Thanks for listening l.jpg

Thanks for listening improved?

For the slides from this talk ..…

www.nal.gov.au


Amplification and directivity l.jpg
Amplification and directivity improved?

50 dBA

80 dBA

Unaided

Aided


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