Collaborative signaling of informational structures by dynamic speech rate

The research reported in this paper is an attempt to elucidate the functions of dynamic speech rates as contextualization cues in conversational Japanese. We examine five spontaneous task-oriented dialogs conducted in Japanese and analyze the potential of speech rate changes in signaling the structure of the information being exchanged in the dialogs. A correlation is found between speech decelerations and the openings of new information, and another is found between speech accelerations and the absence of information openings. These correlations hold not only in the case of a single speaker's speech, but also in the case of multiple speakers' sequential utterances, both with and without turn shifts. On the basis of these findings, we examine the potential of dynamic speech rates as cues to information structures in dialogs, in terms of their precision, recall, and primacy. We claim that changes in the speech rate in conversational Japanese have a definite potential for cuing the structure of information collaboratively constructed by participants of a conversation.