The Effects of Noise Exposure on the Peripheral Vestibular System: An Investigation of Sex Differences and Threshold Shift Following Vestibular Damage

Sex differences in the mammalian auditory system have been observed, however less is known about the vestibular system. While a relationship between loud noise exposure and vestibular dysfunction does exist, studies which examine male and female differences are lacking. This study investigates sex differences in the vestibular periphery of adult Long-Evans rats following noise exposure, sufficient to produce permanent hearing loss, using behavioral and physiological tests. It was hypothesized that female rats would be less susceptible to damage from intense noise exposure, evidenced by smaller changes in vestibular nerve activity and motor function. This hypothesis was tested by measuring vestibular short-latency evoked potentials (VsEP) to evaluate changes in vestibular nerve activity over time, and a balance beam crossing task to evaluate changes in motor performance in the presence of reduced vestibular input. A range of established VsEP stimuli was used in order to investigate a possible threshold shift in vestibular nerve activity.Measurements collected at specific timepoints were compared with baseline values to determine altered vestibular physiology and motor performance over time. Noise exposure worsened the VsEP response, with no sign of recovery over 28 days in any of the rats but did not impair balance beam performance. Sex differences were found in the amplitude of VsEP responses to certain stimuli and more research should be done in order to better understand gender differences is vestibular function, fall risk and response to lifelong noise exposure