The role of segment rate in speech tempo perception by English listeners

Studies in which speech tempo is quantified commonly use either syllable or segment rate as a proxy measure of tempo. Perception studies have shown that syllable rate measurements correlate closely with elicited tempo judgements across languages. Some research suggests that segment rate is an additional, independent predictor of perceived tempo — in other words, that both syllable rate and syllable complexity matter for tempo perception. However, direct empirical evidence for this is as yet lacking. This paper reports on three experiments that test the hypothesis that when segment rate is varied on a constant syllable rate, listeners estimate utterances with higher segment rates as faster. Our results provide evidence for listeners’ orientation to syllable rate in estimating tempo, and evidence for listeners’ additional orientation to segment rate — that is, to syllable complexity. However, the latter orientation is only observable when stimuli are variable in duration: when presented with stimuli that are identical both in syllable rate and duration, listeners do not appear to hear stimuli with more complex syllables as faster.