Temporal structure of repetition disfluencies in American English

A repetition disfluency involves an interruption in the flow of speech followed by a restart, leading to repetition of one or more words. We analyzed the temporal structure of one-word, two-word, and three-word repetition disfluencies in the Switchboard Corpus (none-word = 30546, ntwo-word = 8102, nthree-word = 1606). Comparing durations of words preceding an interruption point to their repeated counterparts, we find that repetition is typically accompanied by prolongation, which mainly influences the last word preceding the interruption point. When prolongation does not provide enough time for planning upcoming speech—as there seems to be a temporal limit to prolongation—the speaker repeats parts of the utterance just produced. Our results demonstrate that the number of words repeated is determined both by word duration and by co-occurrence relations between words. Mixed effects logistic regression analysis revealed that longer words are less likely to be repeated (z=-24.45, p<.0001). However, the number of words repeated does not reduce to duration: controlling for word duration, the more frequent a two-word sequence, the less likely it is to be interrupted by a restart (z=35.43, p<.0001). Longer repetitions are produced when a shorter repetition would result in restarting speech production from the middle of a cohesive word sequence.