This paper studied effects of topic structure and sentence length on acoustic parameters at intonational phrases boundaries, comparing female and male speakers. Twenty native speakers of Mandarin Chinese read 12 short discourses Cwhich contained two sentences. The second sentence was either short or long. And, the transition between the two sentences was either topic continuation, topic elaboration or topic shift, by varying the second sentence. Extensive acoustic analysis showed that [1] for the female speakers, both topic structure and sentence length had significant effects on pause duration and pitch reset, but not on final lengthening, whereas for the male speakers, only sentence length had such an effect. [2] A negative correlation between pause duration and pre-boundary lengthening was found for both the female and the male speakers. However, a positive correlation between pause duration and pitch reset was found only for the females, but not for the males. In general, the female speakers used combined acoustic cues for marking topic structure, whereas the male speakers did not mark topic structure systematically. Effect of sentence length on pause duration is robust while all the other conditions are controlled.

Index Terms: topic structure, sentence length, pause, pitch reset, final lengthening