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Naval Submarine Medical Research Laboratory > Research -- Hearing Conservation

Research -- Hearing Conservation

Evoked Otoacoustic Emissions (EOAEs)

EOAEs are sounds produced by the inner ear that are measurable in the ear canal. Healthy ears produce EOAEs; noise-damaged ears produce fewer, lower, or no EOAEs

Use of EOAEs in DOD Hearing Conservation Programs

NSMRL is evaluating new methods for evoking otoacoustic emissions that are thought to be sensitive to the early stages of noise-induced hearing loss (NIHL), and good indicators of susceptibility to NIHL. We are developing otoacoustic emissions equipment and protocols especially for use in adult hearing conservation programs. Evaluation includes both laboratory and field testing. This congressionally funded project is administered by the Army.

Marine Recruit Study

Hearing and EOAEs were measured in marine recruits before and after basic training, where recruits were exposed to live-fire training. Along with a genetic profile and audiological risk-factors, these data are currently being analyzed to determine which factors, if any, are indicators of susceptibility to noise-induced hearing loss. This study was funded by the Office of Naval Research.

Aircraft Carrier Study

NSMRL measured hearing and EOAEs in 339 sailors before and after a six-month deployment on the USS Dwight D Eisenhower aircraft carrier. Group hearing did not change but group EOAE levels decreased, indicating EOAEs are more sensitive to the early stages of noise-induced damage to the inner ear. This study was funded by the Office of Naval Research.

The Hearing Conservation Team focuses on ways to identify the early stages of noise-induced damage to the human ear.

Our current research involves the evaluation of new methods for evoking otoacoustic emissions that are thought to be (a) sensitive to the early stages of noise-induced hearing loss (NIHL) and (b) a measure of susceptibility to NIHL. Our approach is to evaluate these methods both in the laboratory (for validity, reliability, and sensitivity to temporary noise-induced changes) and in the field with noise-exposed at-risk personnel (for detecting the early stages of permanent noise-induced changes).

 Personnel and Facilities

The hearing conservation team consists of three investigators with Ph.D.s and research experience in speech and hearing sciences, audiology, psychology, and psychophysics; three research associates (a Masters-level audiologist; a Masters-level quantitative analyst, and a computer programmer); and an USN ENT technician certified in hearing conservation.

Auditory facilities include:

  • Five double-walled sound-attenuating audiometric booths
  • Seven portable otoacoustic emissions test stations for laboratory and field studies
 
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