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Is Overshoot Caused by an Efferent Reduction in Cochlear Gain?

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


Mark Fletcher

Jessica de Boer


Under certain conditions, detection of a masked tone is improved by a preceding sound ("precursor"). This phenomenon is referred to as the "temporal effect" or "overshoot". A prevalent model of overshoot, referred to as the "gain reduction model", posits that overshoot is caused by efferent reduction in cochlear gain mediated by the medial olivocochlear (MOC) bundle. The model predicts that reduction in cochlear gain will reduce masking when masking is suppressive or when masking is excitatory and the signal-to-masker ratio is high. This study was aimed at testing the validity of these predictions. It consisted of two experiments. The first experiment investigated the relative contributions of suppressive versus excitatory masking to overshoot. The signal was a short 4-kHz tone pip, and the masker and precursor were limited to contain energy either only within (on-frequency) or only outside (off-frequency) the cochlear filter around the signal frequency. The on-frequency masker would be expected to cause mainly excitatory masking, whereas masking by the off-frequency masker would be expected to be mainly suppressive. Only the off-frequency masker and precursor yielded significant overshoot. This suggests that measurable overshoot requires suppressive masking. The second experiment sought to quantify the effect of a precursor on cochlear suppression more directly by measuring the amount of suppression caused by a 4.75-kHz suppressor on a lower-frequency (4-kHz) suppressee with and without a precursor present. Suppression was measured using a forward-masking paradigm. While we found large suppression and large overshoot, we found no reduction in suppression by the precursor. This is contrary to the gain reduction model. Taken together, our results indicate that measurable overshoot requires off-frequency masking and that off-frequency overshoot must be caused by a mechanism other than MOC-mediated reduction in cochlear suppression. © Springer Science+Business Media New York 2013.


Fletcher, M., de Boer, J., & Krumbholz, K. (2013). Is Overshoot Caused by an Efferent Reduction in Cochlear Gain?. In Basic Aspects of Hearing: Physiology and Perception (65-72).

Conference Name International Symposium on Hearing
Conference Location Cambridge, UK
Start Date Jul 23, 2012
End Date Jul 27, 2012
Online Publication Date May 29, 2013
Publication Date May 29, 2013
Deposit Date Jun 11, 2019
Journal Advances in Experimental Medicine and Biology; Basic Aspects of Hearing
Electronic ISSN 2214-8019
Publisher Springer Verlag
Pages 65-72
Series Title Advances in Experimental Medicine and Biology
Series Number 787
Series ISSN 2214-8019
Book Title Basic Aspects of Hearing: Physiology and Perception
ISBN 9781461415893
Public URL
Publisher URL