ASA 125th Meeting Ottawa 1993 May

4pSP9. Vowel continuity and perception of /ba--wa/.

Andrew J. Lotto

Dept. of Psychol., Univ. of Wisconsin, Madison, WI 53706

Kerry Green

Univ. of Arizona, Tucson, AZ 85721

Keith R. Kluender

Univ. of Wisconsin, Madison, WI 53706

When CV syllables have longer vowels following a stop /b/ or glide /w/, the duration of transition necessary to perceive a stimulus as /w/ is longer as well. Perceived continuity/duration of following vowels was manipulated by exploiting the phenomenon of auditory induction. All syllables were 315 ms in duration, and transition duration was varied from 15--65 ms for four series of syllables. After the first 100 ms of each syllable (transition + vowel), broadband noise either replaced or was added to the second 100 ms of syllable. Noise was either the same intensity as or 12 dB greater than the intensity of the vowel. Results from a signal detection task indicated that listeners could reliably report when the signal was deleted and replaced by the less intense noise; however, they could not reliably report whether the vowel was deleted when the noise was more intense (+12 dB). Listeners were asked to label these four series of stimuli as beginning with /b/ or /w/, and there was no effect of either the presence or absence of the vowel or of noise intensity. Even when subjects's phenomenal experience was one of intact continuous syllables (+12-dB noise with vowel present or absent, or equal intensity noise with vowel present), subjects' labeling boundaries were virtually identical to those for syllables perceived as interrupted (equal intensity noise with vowel absent) or for syllables of only 100-ms total duration. Theoretical implications and results from follow-up experiments will be reported. [Work supported by NIDCD Grant No. DC-00719 and NSF Grant No. DBS-9258482.]