TALKER CONTINUITY AND THE USE OF RATE INFORMATION DURING PHONETIC PERCEPTION

Research has shown that speaking rate provides an important context fo r the perception of certain acoustic properties of speech. For example , syllable duration, which varies as a function of speaking rate, has been shown to influence the perception of voice onset time (VOT) for s yllable-initial stop consonants. The purpose of the present experiment s was to examine the influence of syllable duration when the initial p ortion of the syllable was produced by one talker and the remainder of the syllable was produced by a different talker. A short-duration and a long-duration /bi/-/pi/ continuum were synthesized with pitch and f ormant values appropriate to a female talker. When presented to listen ers for identification, these stimuli demonstrated the typical effect of syllable duration on the voicing boundary: a shorter VOT boundary f or the short stimuli than for the long stimuli. An /i/ vowel, synthesi zed with pitch and formant values appropriate to a male talker, was ad ded to the end of each of the short tokens, producing a new hybrid con tinuum. Although the overall syllable duration of the hybrid stimuli e qualed the original long stimuli, they produced a VOT boundary similar to that for the short stimuli. In a second experiment, two new /i/ vo wels were synthesized. One had a pitch appropriate to a female talker with formant values appropriate to a male talker; the other had a pitc h appropriate to a male talker and formants appropriate to a female ta lker. These vowels were used to create two new hybrid continua. In a t hird experiment, new hybrid continua were created by using more extrem e male formant values. The results of both experiments demonstrated th at the hybrid tokens with a change in pitch acted like the short stimu li, whereas the tokens with a change in formants acted like the long s timuli. A fourth experiment demonstrated that listeners could hear a c hange in talker with both sets of hybrid tokens. These results indicat e that continuity of pitch but not formant structure appears to be the critical factor in the calculation of speaking rate within a syllable .