Evaluation of noise-induced hearing loss with audiometer and distortion product otoacoustic emissions.

OBJECTIVE: To compare the results of audiogram and distortion product otoacoustic emissions (DPOAEs) parameters between staffs working in a noisy environment and normal subjects. MATERIAL AND METHOD: Hearing function of 32 noise-exposed workers and 18 reference subjects were assessed with DPOAEs and pure-tone audiometry. Results were compared among three groups: 1) ears of reference subjects, 2) audiometrically normal ears of noise-exposed subjects, and 3) audiometrically abnormal ears of noise-exposed subjects. RESULTS: DPOAEs parameters, statistically significant difference were found between group 1 and 2 and group 1 and 3 at all frequencies. Statistically significant differences in pass rate for DPOAEs at 4-6 kilohertz (kHz) were also found between group 1 and 2. CONCLUSION: DPOAEs are more sensitive than audiometry to detect pre-symptomatic inner ear damage. It may play a role as screening and monitoring test for noise-exposed workers.