Investigation of hidden hearing loss in normal hearing individuals with tinnitus

Tinnitus is defined as the abnormal sound perception felt by the individual without an external stimulus. Many studies have been conducted to explain the underlying mechanisms of tinnitus. In terms of its perceptual features and accompanying symptoms, the cause of tinnitus is clinically heterogeneous. The aim of this study is to investigate hidden hearing loss, which has been shown as a potential factor for the etiology of tinnitus. According to standard measurements (0.125-8 kHz), 20 individuals with tinnitus (study group) and 20 normal individuals (control group) with normal hearing participated in the study. Pure tone hearing thresholds of the participants were assessed in the range of 0.125- 16 kHz. Afterwards, behavioural and electrophysiological tests were applied to the participants. When the ABR findings of the participants were examined, it was observed that the I. wave amplitudes and V. wave amplitudes of individuals with tinnitus group were lower than those of normal individuals (p<0.05). When the extended high frequency hearing thresholds of the individuals were evaluated, the individuals with tinnitus had higher hearing thresholds (p<0.05). When the TEOAE findings were examined, although there was no significant difference in most frequencies in the tinnitus group, a lower emission response was obtained (p>0.05). As a result of contralateral suppression measurement in both groups, no significant difference was observed in frequencies other than 1000 Hz (p>0.05). In addition, the acoustic reflex threshold was higher in the tinnitus group (p<0.05). When the speech perception skills of the participants were evaluated, the individuals with tinnitus had weaker performances (p<0.05). When the supra-threshold processing skills were examined, individuals with tinnitus performed poorly (p<0.05). When the findings were evaluated, it was thought that tinnitus might be related to the loss of extended high frequency hearing thresholds. The reason for the deterioration of speech perception and suprathreshold processing skills in noise may be related to cochlear damage. Keywords: Tinnitus, Hidden Hearing Loss, Extended High Frequency