Outcomes for wearers of hearing aids and improving hearing aid technology

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Outcomes for wearers of hearing aids and
improving hearing aid technology

• Harvey Dillon
• NAL
• CRC Hear

Denis Byrne Oration Canberra, 2008.
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• Who benefits from hearing aids?
• What can hearing aids do for people with hearing
  loss?
• How can we make hearing aids work better?

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The bits of this talk .

• Whos got hearing aids
• Who should have hearing aids
• Whos got hearing aids but shouldnt
• How people misjudge their hearing
• Why hearing aids are sometimes useless
• How technology is changing candidacy
• Hearing aids of the future
• What we should do differently now

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Who is using hearing aids?Of those with gt25 dB
4FAHL in better ear
Use 23
Australia
Dont have 67
Dont use 10
Source Blue Mountains Study (Mitchell, Hartley
et al)
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Percentage penetration of hearing aids
Mitchell (2002)
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Hearing loss in the future
Sources ABS series B Sth Aust population study
Possible further increase from Personal stereo
use ? ? Rock music ? ? Power tools ? ? Premature
baby survival ? ?
And decrease from War exposure ? Manufacturing
? Rubella epidemics ?
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Growth in people with hearing loss (gt25 dB 4FAHL
better ear)
Blue squares 2.5 compound growth
Over 55 years
Over 65 years
Source Hartley Dillon, unpublished data
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Growth in OHS voucher numbers
Blue squares 9 compound growth
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PenetrationHearing aid owners as a proportion
of those with gt25 dB 4FAHL better ear
OHS vouchers 9
OHS vouchers 5
Hearing impaired growth 2.5
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Conundrum

• Older people more likely to need a hearing aid
• Younger people more likely to adapt well to using
  a hearing aid
• Alberti (1977) Brooks (1985)

Implication We need to know who will benefit from
a hearing aid so those people get them as soon as
possible
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What should penetration be?Who does benefit
from a hearing aid?
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Experiment

• To determine the minimum hearing loss for which
  clients will receive benefit from hearing aids.
• Previous research has not indicated a close
  relationship between benefit and hearing
  thresholds.
• Some people with very mild losses are being
  fitted in the current scheme.
• It is extremely unlikely that people with normal
  hearing would benefit from hearing aids.

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Procedure

• 400 clients sampled from OHS voucher database
• 41,521 new clients fitted Feb to Sept, 2004
• Audiometric and other details obtained from
  selected clients files
• Questionnaire sent to selected clients
• International Outcome Inventory for Hearing Aids
• Plus 6 purpose-designed questions
• Selected clients followed up by phone or
  additional mail to get a high response rate
  (effectively 86)

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Hearing loss characteristics of study sample
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Usage of hearing aids
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Factor analysis of questionnaire
Factor Loadings Factor Loadings Factor Loadings Factor Loadings
Factor 1 Factor 2 Factor 3
Q1 want aids 0.69 0.30 0.21
Q2 difficulty unaided 0.70 0.41 0.25
Q3 use 0.74 -0.18 0.08
Q4 benefit 0.82 -0.32 0.00
Q5 residual difficulty 0.03 -0.76 -0.33
Q6 Worth it 0.83 -0.33 -0.00
Q7 Residual handicap -0.29 -0.56 -0.06
Q8 Bother to others -0.18 -0.68 -0.26
Q9 Quality of life 0.82 -0.32 0.02
Q10 Replace them 0.34 -0.15 -0.23
Q11 Face vision -0.29 -0.42 0.74
Q12 paper vision -0.22 -0.47 0.70
Proportion of variance 0.32 20 0.12
International Outcomes Inventory for Hearing
Aids
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Factor analysis of questionnaire
Factor Loadings Factor Loadings Factor Loadings Factor Loadings
Factor 1 Factor 2 Factor 3
Q1 want aids 0.69 0.30 0.21
Q2 difficulty unaided 0.70 0.41 0.25
Q3 use 0.74 -0.18 0.08
Q4 benefit 0.82 -0.32 0.00
Q5 residual difficulty 0.03 -0.76 -0.33
Q6 Worth it 0.83 -0.33 -0.00
Q7 Residual handicap -0.29 -0.56 -0.06
Q8 Bother to others -0.18 -0.68 -0.26
Q9 Quality of life 0.82 -0.32 0.02
Q10 Replace them 0.34 -0.15 -0.23
Q11 Face vision -0.29 -0.42 0.74
Q12 paper vision -0.22 -0.47 0.70
Proportion of variance 0.32 20 0.12
International Outcomes Inventory for Hearing
Aids
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Simple correlations

• People who more strongly wanted to get hearing
  aids
• Use them more (Q3)
• Benefit from them more (Q4)
• Say they are worth it (Q6)
• Improve their enjoyment of life by using them
  (Q9)
• Would replace their hearing aids if lost (Q10)
• People who had the most difficulty unaided
• Use their hearing aids more (Q3)
• Benefit from them more (Q4)
• Say they are worth it (Q6)
• Improve their enjoyment of life by using them
  (Q9)
• Would replace their hearing aids if lost (Q10)

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Use

Composite Benefit
Benefit

Satisfaction

QOL
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Composite benefit for different daily usage
High use goes with high benefit and vice-versa
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What might account for variation in benefit?

• Hearing loss
• Age
• Gender
• Type of hearing aid
• Difficulty listening unaided
• Original desire to get hearing aids
• Visual ability

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Difficulty hearing unaided and wish to get
hearing aids
Unaided difficulty related to wish to get hearing
aids
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Difficulty listening unaided
Need

Desire to get hearing aids
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Relationship between predictors and outcomes
Composite benefit Composite difficulty
Better ear 3FA 0.09 -0.18
Worse ear 3FA 0.13 -0.17
Better ear 4FA 0.08 -0.23
Worse ear 4FA 0.13 -0.20
Age -0.15 0.03
Need strength 0.51 -0.44
Vision summary -0.08 0.19
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Effect of hearing loss on benefit
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Effect of hearing loss on benefit
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• How is composite benefit related to need?

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Benefit versus need
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I dont wear my hearing aids never did. I
dont know why they gave them to me.-
Participant 1-089
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Benefit for different degrees of hearing loss
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Benefit for different hearing aid types
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Benefit for top-up and free-to-client
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• Are outcomes affected by the provider the client
  goes to?

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Benefit for different contractors
P0.0004
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• Why?

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Hearing loss for different contractors
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Need strength for different contractors
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Which hearing loss or need?

• Allow for differences in hearing loss ?
  difference in benefit remains (p0.002)
• Allow for the differences in need ? difference in
  benefit disappears (p0.33)

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Benefit vs Needs applies to all contractors
Contractors A, B, D and E
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Implication

• Benefit is much more strongly determined by need
  than by hearing loss.
• Need difficulty listening unaided desire to
  get hearing aids in first place

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Why dont people with hearing loss acquire
hearing aids?

• My hearing loss is not bad enough to need them
  (Kochkin, 1993)
• beliefs about difficulties they are having
• beliefs about hearing aid likely benefits
• beliefs about emotional consequences of wearing
  hearing aids
• beliefs about practical issues (expense,
  complexity, manipulation)

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Health belief model

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

Difficulties experienced frequency, severity
Self-image
Hearing aid effectiveness
Ability to manage
Effect on others view
Hearing loss
Cost
Inconven-ience
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Health belief model

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

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Health belief model

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

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Circle of negative beliefs
positive
Hearing aids dont work
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Expectations and benefit

• Higher expectations ? greater use and benefit
  (Jerram Purdy, 2001)
• Higher expectations ? higher benefit (Cox
  Alexander).

Outcomes
Use, benefit
Satisfaction
Expectations
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What can a hearing aid actually do?

1. Amplify soft sounds
2. Emphasise frontal sounds

35 dB 4FA HL
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Amplifying soft sounds
Speech at 55 dB SPL
Speech intelligibility index 0.45 ? Percent
words in sentences correct 93
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Amplifying speech (quiet no reverberation)
People with mild to moderate loss can cope
reasonably well in quiet.
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2. Speech in noise and reverberation

• Noise and reverberation both usually have biggest
  effect on low frequencies

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Amplifying soft sounds
Speech at 55 dB SPL
Speech intelligibility index 0.45 ? Percent
words in sentences correct 93
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Amplifying soft sounds
Speech at 55 dB SPL
Speech intelligibility index 0.24 ? Percent
words in sentences correct 72
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Solution

• A directional microphone to lift the speech in
  front, but not the noise
• but ..

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Room acoustics
SPL
Total
Reverberant
Direct
Critical distance
Distance
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Room acoustics
SPL
Total
Reverberant
Direct
Critical distance
Distance
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Implication for beliefs about hearing?

• Speech with no noise, no reverberation
• ? I can understand!
• My hearing is OK
• Louder speech, noise, reverberation
• I cant understand
• The noise makes it hard to understand,
• (My hearing is fine)

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Implication for beliefs about hearing aids

• Speech with no noise, no reverberation
• ? Hearing aid helps, if needed
• Close speech, directional microphone, noise
  reverberation
• Hearing aid helps
• Distant speech, directional microphone, noise
  reverberation
• Hearing aid doesnt help

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Impact of untreated hearing loss
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Impact of untreated hearing loss on health

• Proven links between hearing loss and
• low mood / emotional state, greater depression
• reduced capability for self-sufficiency,
  restricted social relationships
• reduced life expectancy
• Asserted links between hearing loss and
• loneliness,
• anxiety,
• paranoia,
• exhaustion,
• insecurity,
• loss of group affiliation,
• loss of intimacy,
• anger

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Effects of hearing loss?
Hearing loss
Mortality
Depression
We just cant deduce causation from these surveys
of health
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Effects of hearing aids?
Hearing loss
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Cross-sectional studies
Hearing loss and hearing aids
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Cross-sectional studies
Hearing loss and hearing aids
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Cross-sectional studies
Unwell people, with hearing loss
Healthy people, with hearing loss
Hearing loss and hearing aids
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Longitudinal studies
Mulrow et al (1990) Dye Peak (1983)
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Aged-care facilities
Hearing loss
Appearance of dementia
Improved services ? Improved quality of life
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Technology advances in the last decade

• Integrated wireless receiver
• Adaptive directional microphones
• Multi-channel noise reduction
• Feedback cancelling
• Environment sensing
• Wireless-linked hearing aids
• Impulse noise rejection
• Wax guards
• Data logging
• Integrated rechargeable batteries

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So why no increase in satisfaction?

• Increase in laboratory-measured benefit
• No increase in real-world reported satisfaction

Technology advance
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Some technology advances in the next few years-
from the CRC for Hearing, including NAL

• Trainable hearing aids
• Improved occlusion reduction
• Improved intelligibility in noise

• Hybrid cochlear implants and hearing aids
• Fully implanted devices (implants and hearing
  aids)?

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Moving on from prescriptions

• The trainable hearing aid
• Justin Zakis, Gitte Keidser,
• Hugh Mcdermott, Liz Convery

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Trainable aid general structure
Acoustic measurement module
User control(s)
Learning algorithms
Programmable amplifier
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Aid user adjusts settings...
Trainable Aid
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Aid user adjusts settings...
Trainable Aid
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...the hearing aid takes note
Trainable Aid
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Process repeats for other sounds
Trainable Aid
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After training, preferred settingsare
automatically applied...
Trainable Aid
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After training, preferred settingsare
automatically applied...
Trainable Aid
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After training, preferred settingsare
automatically applied...
Trainable Aid
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After training, preferred settingsare
automatically applied...
Trainable Aid
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Trainable aid philosophy

• Prescribe what can be prescribed, automatically
  and in minimum clinical time
• Leave the rest to the client (and the
  intelligence of the hearing aid)

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Training gain, CT, CR.
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• Active occlusion reduction
• Jorge Mejia, John Coelho (deceased)

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Electronic Venting
?
H/A
-
Canal
Hearing Aid
Cartilage
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Vent and amplification path transmission
Combined path
Amplified path
Vent path
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Occlusion reduction Mean and Standard
Deviation Note that feedback gain was adjusted
for all subjects, filter settings remain the same
(22 ears)
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• Super-directional hearing in noise
• Jorge Mejia

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Improving understanding in noise

• Wireless transmission v v v
• Directional microphones v
• (Adaptive noise suppression)

v
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Physical arrangement simulated
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Loss of SNR in hearing loss
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Blind source separation matrix(Inverse based on
initial 100 ms of signal)
Jorge Mejia
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The result ?

• Hearing impaired people who can understand better
  in noise than people with normal hearing.

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Things in your ears

• Now
• mobile phones,
• MP3 players,
• portable DVD players,
• personal digital assistants,
• and of course .. hearing aids.
• In the future
• personal navigation aids,
• Voice input/output internet connection,
• local area (human communication) wireless
  networks,
• all voice controlled, of course

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What do we mean by hearing loss?

• 2 to 3 of children are estimated to have some
  form of central auditory processing disorder.
• CAPD reduces speech intelligibility in noise,
  just like sensorineural hearing loss.
• CAPD includes a group of different deficits,
  which can be present singly or mutiply.
• CAPD can be compensated for, and can probably be
  remediated as well.

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Messages so far

• Hearing loss is on the increase due (at least) to
  aging
• Motivation is the major determinant of benefit
• Hearing aid penetration is
• low, but
• highest in world, and
• rapidly increasing.
• Fitting hearing aids to people who dont want
  them spreads negative, self-fulfilling stories
• Technology advances have been
• worthwhile, but
• oversold, and
• will continue, or even accelerate

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Aim

• To increase penetration rate of hearing aids
• and
• Increase usage and benefit

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The solution is in the hands of

• Clinicians
• Provider owners
• Government
• Manufacturers
• Researchers

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Clinicians

• Dont fit people who dont seem to want them

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Provider owners

• Provide incentives to clinicians for superior
  outcomes, not just superior sales

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Government

• Pay for outcomes, not for processes

• Current system specifies process
• Payment is made for process
• Quality control inspects the process

• Result
• No control over outcomes
• No financial motivation for providers to improve
  outcomes
• Financial benefit if clients dont wear hearing
  aids
• Financial motivation for providers to maximise
  number of fittings

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Government (cont)

• Alternative scheme

• Pay same for assessment
• Pay less for fitting
• Pay for outcomes

• Result
• Providers with worse than current average
  outcomes earn less
• Providers with better than current average
  outcomes earn more
• Most providers will have better than current
  average outcmes
• Huge saving by government on people who wont be
  fitted

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Government (cont)

• Outcomes measurement

• Just measure
• Use
• Benefit
• Satisfaction
• Quality of life improvement
• Need to allow for
• New versus return clients
• Response rate
• Degree of hearing loss

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Manufacturers

• Continue technology improvements
• Change marketing
• dont oversell
• dont confuse
• Pursue convergence
• hearing aid
• communication device
• hearing protector
• better than normal hearing

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Hearing device of the future

• Pathway to many systems
• Communication
• Information
• Entertainment
• Speech enhancer in noise
• Active hearing protector
• (Hearing aid)

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Noise suppression Adaptive directionality Feedback cancelling
Bernafon
Oticon
Phonak
Siemens
Starkey

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Researchers

• What makes a hearing aid candidate ?
• What other than motivation ?
• How do you measure motivation ?
• How do you change motivation ?
• How beneficial are hearing aid features ?
• For different people
• For different situations

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Future behavioural research

• Why dont some people seek help?
• Why do some people seeking help not get hearing
  aids?
• Why do some who get hearing aids not get benefit?

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Results from Telscreen Testing (n4058) Golding,
2008
N1270
N1001
N850
N485
60.7
38.7
N230
27.7
N124
N36
22.9
24.8
(N 3996) (age range 16-100 years only)
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The life quality of people with hearing loss -
in the hands of

• Clinicians
• Provider owners
• Government
• Manufacturers
• Researchers

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• Thanks for your attention
• Slides will be on the NAL web site
• www.nal.gov.au
• From May 28

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