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Effect of contralateral medial olivocochlear feedback on perceptual estimates of cochlear gain and compression

Fletcher, Mark D.; Krumbholz, Katrin; de Boer, Jessica

Effect of contralateral medial olivocochlear feedback on perceptual estimates of cochlear gain and compression Thumbnail


Mark D. Fletcher

Jessica de Boer


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 optoacoustic 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.

Journal Article Type Article
Acceptance Date Jun 17, 2016
Online Publication Date Aug 22, 2016
Publication Date Dec 31, 2016
Deposit Date Sep 1, 2016
Publicly Available Date Sep 1, 2016
Journal Journal of the Association for Research in Otolaryngology
Print ISSN 1525-3961
Electronic ISSN 1525-3961
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 17
Issue 6
Pages 559-575
Keywords medial olivocochlear reflex (MOCR); temporal masking curve (TMC); click-evoked otoacoustic emissions (CEOAEs); contralateral acoustic stimulation; cochlear amplification
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