Update on Historical Milestones in Audiology

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Update on Historical Milestones in Audiology
Hearing Aids

• Ruth Bentler
• With a little help from my friend, Jim Jerger
• May 29, 2008

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1922

• First commercial audiometer
• Western Electric 1-A
• Harvey Fletcher

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1922

• The audiogram form as we know it today.

Edmund Prince Fowler
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1939

• First book on clinical audiometry
• Cordia C Bunch

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1946

• Speech
• audiometry
• Raymond Carhart

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1960

• Bekesy
• audiometry
• James Jerger

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1962

• First infant screening program
• Marian Downs

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1970

• Impedance audiometry
• James Jerger

Madsen ZO61
Madsen ZO70
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1971
The Auditory Brain Stem Response
(ABR) Donald Jewett
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1974

• Pediatric
• applications
• ABR
• Kurt Hecox Robert Galambos

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Some Audiological Pioneers
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Some Hearing Aid Milestones
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First published accounts

• Pre-electric (prior to 1900)
• Deaf aids
• Deaf instruments
• Speaking tubes (or trumpets)
• Hearing tubes (or trumpets)
• Manufacturers
• Frederick Charles Rein Co (1800-1963)
• T. Hawksley Ltd of London (1869)
• George P. Pilling Sons (1814)
• etc

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First Electric

• 1900
• Big
• Poor frequency
• response

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First programmable

• 1988 (also beginning of multi-memories,
  multi-channels, remotes, etc)
• Bentler (1992) American Journal of Audiology

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First digital

• 1995
• Oticon/Widex
• (Harnack-Knebel Bentler, 1998, Ear Hearing)

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First (and only) disposable

• 1998
• Songbird
• Poor design
• Analog OR Digital

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First signal processor to correct hearing

• Still waiting.

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New (useful) technologies

• Open fittings (plus RITE)
• Directional Microphones
• Digital Noise Reduction
• Feedback management
• Data logging
• Data learning

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Open Fitting (or Open Fitting?)

• Starkey Aspect XtraTM
• Sonic Innovations ionTM
• GN Resound (were sending our competitors back
  to the drawing board) AirTM, PulseTM
• MicroTech SenecaTM
• Oticons Corda tubing option for
• Synchro
• Tego, Tego Pro
• Bernafon SwissEarTM
• Unitron ModaTM
• Widex Inteo elan TM

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How is it that we now do better?

• Feedback cancellation
• Broader bandwidth
• New market

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Directional Microphones
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Quick Tutorial

• Ways to build directivity into a hearing aid
  case
• Single mic with two ports
• Two omni mics
• Combination of omni directional mics
• Three mics
• Mic array

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Directional Microphone
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Reading a Polar Plot
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OmniDirectional Microphone
Polar plot for omnidirectional mic in free field
Level of signal
Angle of signal source
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Polar Response Pattern
Free field characteristics of different types of
microphones (Knowles TB 21)
Omnidirectional Cardioid Hypercardioid
Supercardioid
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Directional Microphones
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Analog NR (1980-90s)

• Early spectral approaches
• Switch
• ASP (means low frequency compression)
• Adaptive filtering
• Frequency dependant input compression
• Adaptive compressionTM
• Zeta Noise BlockerTM

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Todays versions

• Most are modulation-based with some algorithm for
  where and how much gain reduction should occur
• At least one other (Oticon) first introduced a
  strategy called synchronous morphology to
  determine when noise reduction will occur
• Several are now implementing Wiener filters as
  well
• Many also use some mic noise reduction,
  expansion, wind noise reduction, and even
  directional mics as part of the strategy they
  promote.

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New (not-so-useful?) features

• Talking hearing aids
• Talk to person wearing aid
• Talk to each other
• In many languages!
• Complex remote controls
• Sometimes necessary, eg Bluetooth
• Not useful for young and old

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• Questions?