Abstract:
Six adult speakers of American English produced voiceless fricatives and affricates in word initial position in a carrier phrase, varying vowel context, and stress patterns. From each of the productions, the following acoustic measurements were made: silence duration, frication duration, amplitude rise time, amplitude rise slope, frication onset centroid frequency, and following vowel duration. A discriminant function analysis revealed that silence duration was the best at discriminating between the fricatives and affricates, followed by frication duration, onset frequency, and rise slope. No additional discrimination was found due to either rise time or vowel duration. The traditional acoustic measure of rise time, which includes the duration and the slope of the rise, may be due entirely to the contribution of the slope rather than the duration itself. Although rise time has long been considered an important perceptual cue in the distinction between fricatives and affricates, recent research has brought this into question [K. R. Kluender and M. A. Walsh, Percept. Psychophys. 51, 328--333 (1992)]. The results of this study suggest that duration measurements (preceding silence interval and frication duration) are more salient acoustic correlates than amplitude rise-time measures. [Work supported by NIDCD.]