Tinnitus and Normal Hearing: A Study on Contralateral Acoustic Reflex

Purpose: The aim of this study was to evaluate the difference of the contralateral acoustic reflex (AR) threshold between adult subjects with hearing within clinically normal limits, with and without tinnitus. Method: The study sample in this exploratory, descriptive, and comparative study comprised 40 female subjects who were evaluated: 20 had tinnitus and 20 formed the control group. The contralateral AR threshold was evaluated at the frequencies of 500, 1000, and 2000 Hz. Results: Elevated or absent AR thresholds were found only in subjects with complaints of tinnitus. At all frequencies and in either ear, the median AR threshold was higher in the group that complained of tinnitus (100.0 dB; range = 95.0-100.0 dB) compared with the control group (90.0 dB; range = 86.3-95.0 dB; p < .01). There was a statistically significant difference (p < .05) in the group with tinnitus, in each of the frequencies studied and in both the right and left ear. Conclusion: The results suggest that evaluation of the efferent system, through AR, could be an important tool for the differential diagnosis of tinnitus in patients whose hearing was within clinically normal limits.