Modern hearing aids and future development trends

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Modern hearing aids and future development
trends

• Graham Naylor
• Co-Director
• Eriksholm Research Centre
• Denmark

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Outline

• Part 1, The modern hearing aid
• Mechanical construction
• Modern features in more advanced models
• Adjustment flexibility
• Part 2, Expected developments a few glances into
  the future
• Fitting procedures
• Amplification algorithms
• Hearing aid construction
• General trends

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Mechanical construction of a modern hearing aid
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Modern features in more advanced models

• Anti-feedback system
• Prevents whistling

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How feedback happens
Result loud whistling
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What Anti-feedback does
Result NO whistling
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Modern features in more advanced models

• Anti-feedback system
• Prevents whistling
• Directional microphone (dual microphone)
• Improves speech performance in some kinds of
  noisy situations

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Directional microphones
Speech Noise
Traditional Directional
NOISE
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Modern features in more advanced models

• Anti-feedback system
• Prevents whistling
• Directional microphone (dual microphone)
• Improves speech performance in some kinds of
  noisy situations
• Automatic speech/comfort mode switching
• Reduces listening effort

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Automatic speech/comfort mode switching
Loudspeaker
Microphone
Amplifier
Yes !
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Automatic speech/comfort mode switching
Loudspeaker
Microphone
Amplifier
No !
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Modern features in more advanced models

• Anti-feedback system
• Prevents whistling
• Directional microphone (dual microphone)
• Improves speech performance in some kinds of
  noisy situations
• Automatic speech/comfort mode switching
• Reduces listening fatigue
• Automatic regulation of amplification
• No need for Volume Control
• User can forget about aid
• Fewer moving parts more reliable.

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Hearing aid adjustment flexibility
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Number of trimmers (virtual)
11
3
Year
1996
1980
2001
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ConsequencesTo benefit from flexibility, we
must have ..

• Setting of hearing aid by computer
• Intelligent individualized prescription
• Based on (for example)
• Audiogram
• Listening needs (lifestyle)
• Age
• Previous experience of amplification
• Systematic fine-tuning to solve problems
• With guidance from software

All these are now available.
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Expected developments

• A few glances into the future

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Future procedures for fitting hearing aids

• Optimisation driven by the user

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Optimisation driven by the professional (present)
Stage 1 Prescription
Stage 2 Fine-tuning
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Optimisation driven by the user (future)
Stage 2 Fine-tuning
Stage 1 Prescription (same as before)
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Optimisation driven by the user (future)

• Potential advantages
• Avoid need for explanation of auditory
  experience
• Make the patient the owner of the treatment
• More appropriate final setting achieved
• Challenges
• Simple ways of adjustment for patient to use
• Changes in relationship between patient and
  professional.

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Future amplification algorithms

• Adaptive beamforming noise reduction system

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Adaptive beamforming
NOISE
In the future, no cables needed
Clean speech
Noise1
Beamformer Signal Processing
Noise2
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Future hearing aid construction

• Micro Electro-Mechanical Systems (MEMS)

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Microphone and amplifier etched onto silicon
chip together

• Compared to present-day microphones
• Much smaller size
• Fewer moving parts and connecting cables
• Cheaper (eventually)

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Future general trends

• Hearing aids will NOT
• give patients normal hearing again
• Hearing aids will become
• Smaller, more reliable, easier to use
• More advanced per dollar for the patient
• Able to learn how to satisfy the user
• Hearing aid fitting will become
• Better at choosing best solution for the
  individual patient
• More holistic (not just amplification)
• More satisfying for all involved

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THE ENDThank you
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The world of sounds
Low Sound level High
Low Frequency High
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Normal hearing
Low Sound level High
Low Frequency High
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Impaired hearing
Normal hearing
Low Sound level High
Lets amplify the sounds!
Low Frequency High
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Low Sound level High
Low Frequency High
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Low Sound level High
Threshold of discomfort has not increased
Low Frequency High
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Linear amplification with output limiting
Low Sound level High
Low Frequency High
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Compression amplification
Low Sound level High
Low Frequency High
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Which to choose ?

• Linear with output limiting
• Quiet sounds undistorted
• Loud sounds very distorted
• User with Volume Control can adjust amplification
  in reaction to changing environments
• Compression
• All sounds moderately distorted
• Relative levels maintained
• No need for Volume Control
• Best choice depends on
• Type of hearing loss
• Shape of audiogram
• Lifestyle (variety of listening environments)
• Cognitive processing capacity

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Hearing aid adjustment flexibility
10000000
1000000
100000
Number of different settings
10000
1000
100
10
Year
1991
1980
2001