otoacoustic emissions n.
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Otoacoustic Emissions. Low-level sounds produced by the cochlea and recordable in the external ear canal. Spontaneous Click-evoked Distortion Product Stimulus Frequency. History. First described by Kemp (1977 & 1978), But predicted by Gold (1948!)

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otoacoustic emissions
Otoacoustic Emissions
  • Low-level sounds produced by the cochlea and recordable in the external ear canal.
  • Spontaneous
  • Click-evoked
  • Distortion Product
  • Stimulus Frequency
history
History
  • First described by Kemp (1977 & 1978),
  • But predicted by Gold (1948!)
  • Supported by almost simultaneous discovery of OHC motility
  • Movement into Clinical Use:
    • Screening for hearing loss
    • Role in Audiologic Battery
anatomy and physiology
Anatomy and Physiology
  • Generators = Outer Hair Cells
  • “Pre-neural”
  • Low-level event//High level stimuli produce their own distortions
  • Reduction/Loss of emission in NITTS
  • SOAEs correlated to number of rows of OHCs
energy path
Energy Path:
  • “Reverse Traveling Wave” is debated
  • Through Middle Ear: Filtering and attenuation
  • Into ear canal Note: requirement of healthy middle ear and clear outer ear.
clinical utility neonatal hearing screening
Clinical Utility -- Neonatal Hearing Screening
  • Transient and Distortion-Product OAEs
  • Rationale: quick, relatively inexpensive, possibly catching losses in a broader frequency range than ABR
  • NIH (1994) recommended two-stage protocol combining OAEs and ABR
clinical utility in the audiologic battery
Clinical Utility-- in the Audiologic Battery
  • Assessment of cochlear health in site-of lesion testing
  • Objective info on peripheral auditory functioning
  • Correlation to audiogram
  • Assessment of Auditory Efferents through Contralateral Suppression
spectrum of sound in ear canal
Spectrum of Sound in Ear Canal

Stimulus Tones

Emission Frequency

Background Noise

caveats remember
Caveats--Remember:
  • there is more to “Hearing” than a healthy cochlea
  • what lies between your equipment and the source?
  • high level stimuli evoke response from inanimate cavities (e.g. in cadavers)