Towards a perceptual model of speech rhythm: integrating the influence of f0 on perceived duration

Previous accounts of speech rhythm focus mainly on duration. For example, the normalised Pairwise Variability Index for vocalic intervals (nPVI-V) quantifies relative duration differences between successive vocalic intervals. Prototypical syllabletiming is characterised by small differences in duration, prototypical stress-timing by large differences. However, differences in f0 between vocalic intervals are thought to influence the perception of duration. This paper (1) quantifies the influence of differences in f0 on perceived duration in a perception experiment, and (2) suggests a modified PVI (nPVI-V(dur*f0)) that takes account of this influence. The new nPVI-V(dur*f0) is then applied to a speech corpus of (stress-timed) British English and (syllable-timed) Indian English. The results are compared to the application of the old nPVI-V, which takes into account duration only, to the same data set.