Features of pauses and conjunctions at syntactic and discourse boundaries in Japanese monologues

Syntactic and discourse boundaries are signalled by prosodic cues as well as linguistic cues in speech. We investigated whether there is a correspondence between prosodic or linguistic cues and the boundary strengths. We measured the rates of filled pauses (FPs) and conjunctions, and the durations of silent and filled pauses and conjunctions at four types of boundaries in casual presentations in Japanese. The results showed that the rates of FPs and conjunctions and the durations of silent pauses correspond to the boundary strengths. However, no significant correspondence was found between the duration of FPs or conjunctions and the boundary strengths. The results suggest that how long the speaker pauses and whether he or she utters a FP or a conjunction is relevant to the boundary strengths. However, the durations of FPs and conjunctions are likely to be affected by the other factors such as planning difficulties of the following parts of speech.