Perception of rhythm in sequences of clicks and of syllables

The perception of speech rhythm may be affected by two factors, one being a tendency, by speakers, to lengthen syllables as the utterance progresses, the other being a tendency, by listeners, to impose rhythmic structure on speech sequences. Three tests were constructed in which each stimulus consisted of a sequence of six sounds and each test contained seven different time-altered stimuli. The time alteration was of a nonlinear progressive nature. Test I consisted of sequences of six clicks; Tests II and III consisted of sequences of six [ta] and six [na] syllables, respectively. Native speakers of English, French and Japanese were asked to rate the regularity of the sequence as accelerating, regular, or decelerating. Results indicate that a stimulus may have values of the alteration parameter which cover a large range and yet still be perceived as regular. However, in all cases, the stimulus that would be produced using the values corresponding to a subject's perception of regularity would be acoustically anisochronous: the timing of this stimulus would always be decelerated. No significant difference in performance was found between English, French and Japanese subjects, nor between click, [ta], and [na] stimuli, nor between the six test orders. The DL for irregularity could not be measured accurately, but it was estimated. A further experiment will be necessary to determine this DL more accurately.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat