Synchronous speech and speech rate

Synchronously read speech has been shown to reduce a high degree of variability exhibited by speakers in laboratory recording: e.g., pause duration and placement, and speech rate. However, quantitative analysis of speech rate variation per se has rarely been reported in studies on synchronous speech. This study examines global and local patterns of speech rate variation in Mandarin Chinese, which is expected to show a relatively stable speech rate variation as measured in the number of syllables per second. The speech data were analyzed and compared in terms of mean speech rate and the variations within a subject, across subjects, and across dialects. Our findings show that speakers exhibit lower and less variable speech rates when they read together than when they read alone. This global pattern is consistently observed across dialects maintaining the unique local variation patterns of speech rate for each dialect. We conclude that simultaneous speakers lower their speech rates when reading together such that the variability of speech rates found in simultaneous speakers is ensured to decrease by lowering speech rate in both global and local patterns. This characteristic is a hallmark of synchronous speech.