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Detecting incipient inner-ear damage from impulse noise with otoacoustic emissions
Lynne Marshall1, Judi A Lapsley Miller, Laurie M Heller
1Naval Submarine Medical Research Laboratory, Groton, Connecticut 06349-5900, USA. lynne.marshall@med.navy.mil
The Journal of the Acoustical Society of America
|February 12, 2009
Summary
Otoacoustic emissions (OAEs) are more sensitive than audiometric thresholds for detecting noise-induced hearing changes. Low-level OAEs indicate a significantly increased risk of future hearing loss in military personnel.
Area of Science:
- Audiology
- Occupational Health
- Military Medicine
Background:
- Military training involves exposure to impulse noise, a known risk factor for hearing damage.
- Traditional audiometric thresholds may not detect early signs of noise-induced hearing loss.
- Otoacoustic emissions (OAEs) offer a sensitive measure of cochlear outer hair cell function.
Purpose of the Study:
- To compare the sensitivity of OAEs and audiometric thresholds in detecting hearing shifts after noise exposure in U.S. Marine Corps recruits.
- To investigate the predictive value of pre-exposure OAE levels for subsequent noise-induced hearing loss.
Main Methods:
- Audiometric thresholds and OAEs were measured in 285 recruits before and after noise exposure.
- A control group of 32 non-noise-exposed individuals was included for comparison.
- Significant threshold shifts (STSs) and significant emission shifts (SESs) were identified using standardized criteria.
Main Results:
- Ears with low-level or absent pre-exposure OAEs were more likely to develop STSs.
- Noise-exposed recruits showed decreased OAE amplitude without changes in audiometric thresholds.
- SESs were more frequent than STSs, and OAEs demonstrated greater sensitivity in detecting hearing changes.
Conclusions:
- OAEs are more sensitive than audiometric thresholds for early detection of noise-induced hearing changes in military settings.
- Pre-existing low-level OAEs are a significant risk factor for developing future hearing loss.
- OAE measurements can enhance hearing conservation programs by identifying individuals at higher risk.
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