Tempo changes typically affect pause durations more than articulation rate. We investigated this phenomenon using synchronous speech, a laboratory version of joint speech, which occurs naturally for example in demonstrations, sports events and religious gatherings. Subjects synchronized with stimuli of varying tempo modified from original recordings by uniform stretching. Responses were compared to stimuli in terms of the number of pauses, durations of pauses and interpause intervals (IPI), as well as latencies measured at the beginning and end of the IPI. All subjects successfully synchronized with all stimuli. Contrary to stimuli, responses contained more pauses at slower tempos, and the proportion of total pause duration was greater at slower tempos. Latencies at IPI end were greater for faster tempos and more negative for slower tempos. Latencies varied more at pause end than at IPI end. Results support the assumption that pause is more elastic than articulated speech. Speakers tend to follow this pattern even when they successfully synchronize with stimuli created artificially with uniform stretching. Although speakers can produce pauses and IPIs which match the durations of the stimuli, they have difficulty when they need to combine pause and IPI durations appropriate to different tempos.