Effect of Contralateral Medial Olivocochlear Feedback on Perceptual Estimates of Cochlear Gain and Compression

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• 作者：Mark D. Fletcher ; Katrin Krumbholz…
• 关键词：medial olivocochlear reflex (MOCR) ; temporal masking curve (TMC) ; click ; evoked otoacoustic emissions (CEOAEs) ; contralateral acoustic stimulation ; cochlear amplification
• 刊名：JARO - Journal of the Association for Research in Otolaryngology
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：17
• 期：6
• 页码：559-575
• 全文大小：2,479 KB
• 刊物类别：Medicine
• 刊物主题：Medicine & Public Health
  Otorhinolaryngology
  Neurosciences
  Neurobiology
  
• 出版者：Springer New York
• ISSN：1438-7573
• 卷排序：17

文摘

The active cochlear mechanism amplifies responses to low-intensity sounds, compresses the range of input sound intensities to a smaller output range, and increases cochlear frequency selectivity. The gain of the active mechanism can be modulated by the medial olivocochlear (MOC) efferent system, creating the possibility of top-down control at the earliest level of auditory processing. In humans, MOC function has mostly been measured by the suppression of otoacoustic emissions (OAEs), typically as a result of MOC activation by a contralateral elicitor sound. The exact relationship between OAE suppression and cochlear gain reduction, however, remains unclear. Here, we measured the effect of a contralateral MOC elicitor on perceptual estimates of cochlear gain and compression, obtained using the established temporal masking curve (TMC) method. The measurements were taken at a signal frequency of 2 kHz and compared with measurements of click-evoked OAE suppression. The elicitor was a broadband noise, set to a sound pressure level of 54 dB to avoid triggering the middle ear muscle reflex. Despite its low level, the elicitor had a significant effect on the TMCs, consistent with a reduction in cochlear gain. The amount of gain reduction was estimated as 4.4 dB on average, corresponding to around 18 % of the without-elicitor gain. As a result, the compression exponent increased from 0.18 to 0.27.