The effect of longitudinal noise exposure on behavioral audiograms and transient-evoked otoacoustic emissions.
The ear vulnerability of a group of combat soldiers was tested. The study initially included 84 soldiers and lasted two years. The soldiers were exposed to the noise of small-arms fire. Measurements included transient-evoked otoacoustic emissions (TEOAE) and pure-tone audiometry. Measurements, initially performed prior to the soldiers' basic training, were repeated several times during the study. In general, TEOAE levels (Em) decreased over time. About 57% of the ears developed a slight hearing loss (SHL) after two years of noise exposure. We define SHL as a threshold shift of 10 dB or greater, in at least at one of the audiometric frequencies 1000, 2000, 3000, 4000, or 6000 Hz. About 63% of the tested ears that had medium TEOAE level (1<Em<8 dB SPL) prior to the noise exposure, developed SHL. On the other hand, among the ears whose Em were either very low (Em< or =1 dB SPL) or very high (Em> or =8 dB SPL), less than 30% developed SHL. We suggest a prediction for ear vulnerability on the basis of Em prior to noise exposure.
Duvdevany
Amnon
A
Acoustics & EMR Section, Medical Corps, IDF, Israel.
Furst
Miriam
M
D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D001299:Audiometry / Q000379:methods*; D001309:Auditory Threshold / Q000502:physiology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data; D008954:Models, Biological; D009622:Noise / Q000009:adverse effects*; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*