Contralateral Acoustic Reflex Growth Functions in Patients with Tinnitus Having Normal Hearing Sensitivity

Abstract Background: An extensive scientific inquiry continues into the generation and pathophysiological changes allied with tinnitus, yet clarity remains ambiguous. Evidence reports that an atypical shift in the nonlinear cochlear process in input–output (I/O) functions may be connected with or contribute to tinnitus generation. However, the relationship between acoustic reflex (AR) and tinnitus in estimating I/O functions remains inadequately acknowledged and unexplored. The present study investigates contralateral AR and AR growth functions (ARGFs) in patients with tinnitus having clinically normal hearing. Methods: A group of 15 individuals with tinnitus (Group I) and 15 without tinnitus (Group II) was considered to measure contralateral AR and ARGF at elicitor frequencies of 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. The AR threshold, AR amplitude, and ARGF slope were estimated and compared between the groups. Results: The findings suggest an earlier AR with a disproportionally larger response amplitude as the elicitor intensity increased, with no plateau recognized at higher intensities for Group I. In addition, the slope of I/O functions was linearized in Group I participants compared to those in Group II. Conclusion: The findings demonstrated a difference in contralateral AR and ARGF between individuals with and without tinnitus having normal hearing sensitivity. The observed difference between the groups could be attributed to a potential deficit in cochlear outer hair cells functioning or efferent inhibitory mechanism in individuals with tinnitus.