Listeners’ sensitivity to syllable complexity in spontaneous speech tempo perception

Studies of speech tempo commonly use syllable or segment rate as a proxy measure for perceived tempo. While listeners’ sensitivity to syllable rate is well-established [1-4], evidence for listeners’ additional sensitivity to segment rate--that is, to syllable complexity alongside syllable rate--is as yet lacking. In [5, 6] we reported experiments that yielded no evidence for listeners’ orientation to segment rate differences between stimuli that have the same syllable rate. In these experiments, we kept syllable rate constant by equalizing phrase durations. As phrase duration is a separate temporal parameter from syllable rate, we must complement this work with experiments using less homogeneous stimulus sets. In this paper we report on an experiment that uses stimuli selected from a corpus of spontaneous British English speech. Within crucial subsets there was minimal variation in one out of syllable and segment rate, and substantial variation in the other. Stimulus duration varied independently. Listeners ranked stimuli for perceived tempo. Results suggest that faced with these more variable stimuli, listeners do orient to segment rate in ranking stimuli that have near-identical syllable rates--presumably reflecting the influence of syllable complexity. Moreover, stimulus duration emerges as a separate factor influencing listeners’ rankings, alongside f0 and intensity.