Impact of Mild Noise Exposure on Cochlear Auditory Evoked Potentials
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Date
2013-05
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The Ohio State University
Abstract
Noise that induces threshold shift, either permanent or temporary, has been shown to induce significant changes in the afferent pathway from the cochlear hair cells to the auditory nerve. This noise-induced de-afferentation of the cochlea can be detected and assessed using Electrocochleography (EcochG), a set of auditory evoked potentials that reflects activation of the cochlea by sound. Whether threshold shift is required to induce de-afferentation of the cochlea is unknown. The purpose of the current experiment was to examine the effect of a one-time mild noise exposure that does not induce threshold shift on the cochlear afferent pathway from the inner hair cells (IHC). In this study, a group of seven male and female Fischer 344 rats were tested. These animals were exposed to a one-time noise exposure (narrowband noise centered at 10 kHz with a bandwidth of 10 kHz presented at 70 dB SPL) that was not intense enough to cause either a temporary or permanent threshold shift. The animals were then tested with EcochG in order to monitor the cochlear microphonic (CM) and the compound action potential (CAP) components to detect any cochlear de-afferenation induced by noise. The testing was repeated once per month for a period of six months to determine any long term changes in the cochlear physiology as a result of the noise exposure. The results demonstrated that significant differences were detected in the CAP amplitudes after the noise exposure, but there were no changes in the CM-CAP ratio over the test period of six months. The stability of the CM-CAP ratio suggests that threshold shift is required for a noise to induce significant cochlear de-afferentation.
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Social and Behavioral Sciences
Arts and Sciences
Arts and Sciences
Keywords
Impact of Mild Noise Exposure