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

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

Abstract

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.

Citation

Fletcher, M. D., Krumbholz, K., & de Boer, J. (2016). Effect of contralateral medial olivocochlear feedback on perceptual estimates of cochlear gain and compression. Journal of the Association for Research in Otolaryngology, 17(6), 559-575. https://doi.org/10.1007/s10162-016-0574-8

• 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
• DOI: https://doi.org/10.1007/s10162-016-0574-8
• Keywords: medial olivocochlear reflex (MOCR); temporal masking curve (TMC); click-evoked otoacoustic emissions (CEOAEs); contralateral acoustic stimulation; cochlear amplification
• Public URL: https://nottingham-repository.worktribe.com/output/831188
• Publisher URL: http://link.springer.com/article/10.1007/s10162-016-0574-8