Evaluation of Synaptopathy by Use of Latency Shift of Wave V Auditory Brainstem Response in the Presence of Ipsilateral Noise

Background and Aim: Recreational and occupational noise can cause permanent  damage to the inner ear. Cochlear synaptopathy can be “hidden” because this synaptic reduction can occur without permanent hearing threshold changes. Our study aimed to assess synaptopathy in people with and without a history of occupational noise exposure by use of latency shift of wave V with masking. 
Methods: In this study, 38 males were involved. All participants had normal hearing thresholds. Of 38 males, 20-male identified with exposure to occupational noise and 18 identified without occupational noise exposure. Auditory brainstem response and masked were performed. 
Results: The main effect of the between-group factor was not significant in the right and left ears. But the main effect of the within-group factor in the right and left ears were significant (p<0.001 and p<0.001). Auditory brainstem response latencies at different levels in each group were significant. These results showed that there were no significant differences between latency changes in both groups. 
Conclusion: In order to diagnose cochlear synaptopathy in humans it is important to use audiological test batteries in the future. There is currently no effective way to diagnose noise- induced cochlear synaptopathy in human subjects. 
Keywords: Noise induce cochlear synaptopathy; auditory brainstem response; cochlear synaptopathy; hidden hearing loss