Asymmetries in vowel-fricative and fricative-vowel information

Abstract

Vocalic formant transitions have been shown to affect identification of both initial and final fricatives. However, Soli and Mann [J. Acoust. Soc. Am. Suppl. 1 73, S53 (1983)] found that transitions did not contribute as much to final as to initial fricative identification. The present study extends that work by manipulating the digitized waveform of spoken words (“sack,” and “shack,” “Cass,” and “cash”). Fricative continua were created by combining the natural /s/ and/ /∫ fricative noises in varying proportions. The vocalic segments, including initial or final transitions, were played forward or backward, so both types of transitions occurred in both positions. In each of these conditions, the individual pitch periods were either in their original direction or reversed (to control for the odd voice quality of reversed speech). Preliminary results with adult listeners show that both types of transitions are less influential with final fricatives than with initial fricatives. This seems to indicate that different perceptual strategies are used for different parts of the syllable. [Work supported by NIH Grant No. HD-01994.]