ASA 127th Meeting M.I.T. 1994 June 6-10

4pSP19. The internal structure of phonetic categories is robust.

Philip Hodgson

Joanne L. Miller

Dept. of Psychol., Northeastern Univ., Boston, MA 02115

Earlier data were presented that underscored the fine-grained internal structure of phonetic categories and the dependence of this structure on the multiple acoustic properties underlying a given phonetic segment [J. Acoust. Soc. Am. 92, 2464(A) (1992)]. Specifically, it was shown that two properties specifying the distinction between stay and say F1 onset frequency and silence duration preceding F1 onset, enter into a within-category trading relation, as revealed by category goodness judgments of stay: These properties jointly determine which variants are perceived as the best exemplars of stay. The current study examined the robustness of these effects. It was found that both the fine-grained category structure and the within-category trading relation were maintained even when the stimuli were presented in multitalker ``babble'' noise at an adverse S/N ratio (0 dB). Moreover, we found that these effects held for sinewave replicas of the speech stimuli, for fully half of the subjects tested (the other half yielding a variety of response patterns, as is typical of sinewave speech). These findings attest to the robustness of within-category structure, including its dependence on multiple acoustic properties. Such robustness would be expected if within-category structure plays a central role in the perception of speech. [Work supported by NIH.]