The MOC Reflex During Active Listening to Speech PurposeThe purpose of this study was to test the hypothesis that active listening to speech would increase medial olivocochlear (MOC) efferent activity for the right vs. the left ear.MethodClick-evoked otoacoustic emissions (CEOAEs) were evoked by 60-dB p.e. SPL clicks in 13 normally hearing adults in 4 test conditions for each ... Article
Article  |   October 01, 2011
The MOC Reflex During Active Listening to Speech
 
Author Affiliations & Notes
  • Theodore Glattke
    University of Arizona, Tucson
  • Barbara K. Cone
    University of Arizona, Tucson
  • Correspondence to Angela C. Garinis, who is now with the University of Washington: agarinis@u.washington.edu
  • Editor: Robert Schlauch
    Editor: Robert Schlauch×
  • Associate Editor: Stanley Gelfand
    Associate Editor: Stanley Gelfand×
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Professional Issues & Training / Speech, Voice & Prosody / Hearing
Article   |   October 01, 2011
The MOC Reflex During Active Listening to Speech
Journal of Speech, Language, and Hearing Research, October 2011, Vol. 54, 1464-1476. doi:10.1044/1092-4388(2011/10-0223)
History: Received August 13, 2010 , Revised December 20, 2010 , Accepted March 17, 2011
 
Journal of Speech, Language, and Hearing Research, October 2011, Vol. 54, 1464-1476. doi:10.1044/1092-4388(2011/10-0223)
History: Received August 13, 2010; Revised December 20, 2010; Accepted March 17, 2011
Web of Science® Times Cited: 16

PurposeThe purpose of this study was to test the hypothesis that active listening to speech would increase medial olivocochlear (MOC) efferent activity for the right vs. the left ear.

MethodClick-evoked otoacoustic emissions (CEOAEs) were evoked by 60-dB p.e. SPL clicks in 13 normally hearing adults in 4 test conditions for each ear: (a) in quiet; (b) with 60-dB SPL contralateral broadband noise; (c) with words embedded (at −3-dB signal-to-noise ratio [SNR]) in 60-dB SPL contralateral noise during which listeners directed attention to the words; and (d) for the same SNR as in the 3rd condition, with words played backwards.

ResultsThere was greater suppression during active listening compared with passive listening that was apparent in the latency range of 6- to 18-ms poststimulus onset. Ear differences in CEOAE amplitude were observed in all conditions, with right-ear amplitudes larger than those for the left. The absolute difference between CEOAE amplitude in quiet and with contralateral noise, a metric of suppression, was equivalent for right and left ears. When the amplitude differences were normalized, suppression was greater for noise presented to the right and the effect measured for a probe in the left ear.

ConclusionThe findings support the theory that cortical mechanisms involved in listening to speech affect cochlear function through the MOC efferent system.

Acknowledgments
Andrew Lotto, Brad Story, David Velenovsky, and Mark Bergstrom provided useful discussion, critique, and technical assistance for this investigation and present article. We gratefully acknowledge their contributions. Portions of this work were presented at the Association for Research in Otolaryngology (ARO), 31st Annual Midwinter Meeting (February 2008; Phoenix, AZ) and at the American Auditory Society Annual Meeting (March 2008; Phoenix, AZ).
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