ASA 125th Meeting Ottawa 1993 May

2pPP12. Time-frequency analyses of coherent frequency fluctuations among spontaneous otoacoustic emissions.

Edward M. Burns

Speech and Hear. Sci., JG-15, Univ. of Washington, Seattle, WA 98195

James W. Pitton

Univ. of Washington, Seattle, WA 98195

Previously it has been shown [e.g., Keefe et al., J. Acoust. Soc. Am. Suppl. 1 88, S17 (1990)] that in ears with multiple spontaneous otoacoustic emissions (SOAEs) there are often short-term amplitude fluctuations that are highly correlated (either positively or negatively) among SOAEs widely separated in frequency. In this report it is shown that in many such ears there are also coherent frequency fluctuations among widely spaced SOAEs. However, the demonstration of these small (a few tenths of a percent), short-term frequency fluctuations is difficult using the usual spectrogram-based analysis because of the inability of the spectrogram to accurately resolve frequency-modulated signals. To circumvent this drawback, advanced time-frequency representations (TFRs) have also been employed: e.g., the cone kernel TFR and the Wigner distribution. These time-frequency representations provide additional insights into the nature of the short-term frequency and amplitude fluctuations in SOAEs. [Work supported by NIDCD.]