Impact of Tinnitus on Cochlear Dysfunction and Electromotile Responses of Outer Hair Cells

Abstract

Objective: Tinnitus is defined as the perception of sound in the absence of an external source. It affects a significant proportion of the adult population and can have a detrimental psychological influence even in people with normal hearing. The aim of this study was to investigate the possible changes in cochlear function in the presence of tinnitus despite normal hearing using the Distortion Product Otoacoustic Emission Input/Output function. Methods: Thirty-two patients aged 18-45 years (26 ± 6.45), including 12 patients with chronic subjective tinnitus and 20 patients without tinnitus, with normal hearing were included in the study. After a detailed ENT examination, evaluations including pure tone audiometry, immittancemetric evaluation, tinnitus evaluation, and distortion product otoacoustic emission input/output tests were performed. Results: In the chronic subjective tinnitus group, the mean tinnitus intensity was 45.58 ± 16.1 dB. When the distortion product otoacoustic emission input/outputt values of the individuals with chronic subjective tinnitus were compared with those of the control group, significantly reduced amplitude responses were obtained at all frequencies (500-10 000 Hz) and at all intensity levels (40-70 dB) in the individuals with tinnitus. Conclusion: In conclusion, the distortion product otoacoustic emission input/outputt test, which is a valuable tool for the assessment of cochlear function and hearing sensitivity in normal hearing individuals, was shown to be useful in individuals with chronic subjective tinnitus. In our study, we demonstrated the effects of tinnitus-induced cochlear dysfunction by a decrease in the amplitude of distortion product otoacoustic emission input/output responses at all frequencies tested.