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

Fletcher, Mark D. and Krumbholz, Katrin and de Boer, Jessica (2016) Effect of contralateral medial olivocochlear feedback on perceptual estimates of cochlear gain and compression. Journal of the Association for Research in Otolaryngology . ISSN 1525-3961

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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.

Item Type: Article
Keywords: medial olivocochlear reflex (MOCR); temporal masking curve (TMC); click-evoked otoacoustic emissions (CEOAEs); contralateral acoustic stimulation; cochlear amplification
Schools/Departments: University of Nottingham UK Campus > Faculty of Medicine and Health Sciences > School of Medicine
University of Nottingham UK Campus > Faculty of Science > School of Psychology
Identification Number: https://doi.org/10.1007/s10162-016-0574-8
Depositing User: Eprints, Support
Date Deposited: 01 Sep 2016 14:13
Last Modified: 16 Sep 2016 09:10
URI: http://eprints.nottingham.ac.uk/id/eprint/36187

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