CONTRALATERAL SUPPRESSION OF EVORKED OTOACOUSTIC EMISSIONS IN NORMAL HEARING SUBJECTS AND IN PATIENTS UNDER STREPTOMYCIN TREATMENT

Abstract

Otoacoustic emissions (OAEs) are sounds, usually subaudible that can be recorded from the ear canal. Early ototoxicity may be detected by OAEs which allow an assessment of impending cochlear dysfunction before subjective hearing loss can be recognized. The OAEs level can be influenced by the suppression effect of the olivocochlear bundle (OCB) system. This study was designed to evaluate the suppression phenomena in normal hearing subjects and in patients under streptomycin treatment.

This was achieved by examining 100 subjects which were classified into two groups (control and study). The age of both groups ranged from 17 to 40 years. The control group consisted of fifty subjects with normal hearing sensitivity. They have no history of otological disorder, use of ototoxic drugs or exposure to long term noise. Study group was further subdivided into two subgroups:Group A: 25 subjects had normal hearing threshold level while they were receiving streptomycin treatment.