Towards an integrated understanding of speaking rate in conversation

We investigate factors that affect speaking rate in conversation, using large corpora of conversational telephone speech in English and Chinese. We find that speaking rate as a function of turn length rises rapidly for turns from one to seven words; remains level (when final words are included) or falls gradually (if final words are excluded) for turns of medium length; and rises slowly for longer turns. When talking with strangers or discussing certain topics, people tend to use longer turns but slower speech rates. In general older people have a slower speech, and males tend to speak slightly faster than females. Finally, we find that the effect of L1 (native language) on L2 (second language) speaking rate is L1 dependent.