Title page for ETD etd-11302009-221114


Document Type Master's Dissertation
Author Van Zyl, Altelani
Email altelani@yahoo.com
URN etd-11302009-221114
Document Title Effect of prolonged contralateral acoustic stimulation on TEOAE suppression
Degree MCommunication Pathology
Department Communication Pathology
Supervisor
Advisor Name Title
Prof J W Hall Co-Supervisor
Prof D C D Swanepoel Supervisor
Keywords
  • transient evoked otoacoustic emissions
  • prolonged stimulation
  • medial olivocochlear efferent system
  • contralateral stimulation
Date 2009-09-01
Availability unrestricted
Abstract
Although the suppressive effect of the medial olivocochlear system (MOCS) on peripheral auditory active mechanisms is well documented in humans, the effect of efferent inhibition over prolonged periods of acoustic stimulation is less well documented, especially as observed in suppression of transient evoked otoacoustic emissions (TEOAE’s). The present study therefore evaluated the relationship between the duration of contralateral acoustic stimulation and the suppression of TEOAE’s in ten adults with normal hearing. TEOAE recordings with linear clicks (60 dB sound pressure level) were measured at four intervals during 15 minutes of continuous contralateral white noise (45 dB sound pressure level), followed by two post-noise recordings. An identical within-subject control condition was recorded without contralateral noise. Experimental and control measurements were repeated three times, on separate days. Results revealed significant and sustained TEOAE amplitude reduction for the entire duration of contralateral stimulation. Suppression increased across the duration of contralateral noise, but not sufficiently to be statistically significant. After noise termination, TEOAE amplitudes increased to values significantly above control recordings. The sustained suppression of TEOAE’s indicates continuous efferent inhibition over time in normal adults, with a significant increase in TEOAE amplitude after noise cessation possibly indicating increased outer hair cell responsiveness after prolonged contralateral noise.

© 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Van Zyl, A 2008, Effect of prolonged contralateral acoustic stimulation on TEOAE suppression, MCommunication Pathology dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11302009-221114/ >

E1539/ag

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