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published_or_final_version / abstract / Speech and Hearing Sciences / Master / Master of Science in Audiology

THE DEPARTMENT OF SPEECH PATHOLOGY AND AUDIOLOGY. FACULTY OF ARTS, UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG In partial fulfillment of the requirements for the degree of Master of Arts by coursework in Audiology June 1999 / High stimulus repetition rates have been proposed as a solution to the poor sensitivity and specificity of the standard electrocochleogram. The use of this approach has been confounded, however, by conflicting literature reports on the effects of high stimulus repetition rates on normal subjects. This study aimed to confirm the effects of high stimulus repetition rates on normal hearing subjects as a precursor to clinical high stimulus repetition rate electrocochleography trials. Electrocochleogram tracings were recorded binaurally from 51 normal hearing subjects at 7.1 cps, 51.1 cps, 101.1 cps and 151.1 cps and the summating potential and action potential latencies and amplitudes, summating potential/action potential amplitude ratios and waveform widths were recorded. Statistical analyses showed that increasing the stimulus repetition rate caused statistically (p<O.05) and clinically (p<O.O1 for latency and p<O.005 for amplitude) significant changes to the action potential latency and amplitude, summating potential/action potential amplitude ratio and waveform width, but caused only limited statistical (p<O.05) and clinical (p<O.OI for latency and p<O.005 for amplitude) changes to the summating potential amplitude and latency. Subject age had no effect on the results and there was no interaction between age and stimulus repetition rates. These findings provide the most comprehensive data on the effects of fast stimulus repetition rates to date, and have provided the beginnings of a valid clinical normative database for high stimulus repetition rate tympanic electrode electrocochleography.

Thesis (M. Sc.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

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The objectives of the investigation were to establish diagnostic reference data; and to examine and report on the effects of sex difference and contralateral masking on the normal BAER. BAERs were elicited from the target (R) ear using clicks presented at 70dBnHL both in the absence and presence of three (50, 6O and 70dBHL) levels of contralateral broadband masking noise. Relevant latency and amplitude data were obtained from 60 selected normal hearing Indian undergraduate female (N=30; X age = 20.33 years) and male (N=30; X age = 21.33 years) students aged between 18 and 25 years (X age = 20.73 years). Diagnostic reference data were established for the absolute latencies of peaks I to VI; relative latencies of peaks I-III; III-V and I-V; absolute amplitudes of peaks I and V and the relative amplitude ratio of peaks V:I. The application of the MANOVA revealed an overall significant (p < 0,05) sex difference effect while no significant differences were observed between the masked and non-masked normal BAER. Furthermore, there were no significant overall interactional effects of sex difference and masking on the BAER. These results are discussed in terms of the literature and implications for clinical application and further research. / Thesis (M.Sc.)-University of Durban-Westville, 1989.