A method for studying variability in fricatives using dynamic measures of spectral mean

This paper presents a new method for studying within-speaker variability in fricative spectra. In this method, nonlinear regression is used to predict values of the spectral mean of a 10-ms window of frication noise from its position in the fricative. The resulting measure of model fit, R-2, is used as an index of within-speaker variability. This method was applied to a co rpus of /s/ and /f/ tokens spoken by three groups of participants: 3-4-year -old children, 7-8-year-old children, and adults. Results indicated that fr icatives were more variable when produced before the stop consonant /p/ tha n before /t/. No difference in variability was noted between adults and chi ldren, although a nonsignificant trend of decreased variability in adults w as noted. (C) 2001 Acoustical Society of America.