Between-speaker and within-speaker variation in speech tempo of American English

This study characterizes the speech tempo (articulation rate, excluding pauses) of two distinct varieties of American English taking into account both between-speaker and within-speaker variation. Each of 192 speakers from Wisconsin (the northern variety) and from North Carolina (the southern variety), men and women, ranging in age from children to old adults, read a set of sentences and produced a spontaneous unconstrained talk. Articulation rate in spontaneous speech was modeled using fixed-mixed effects analyses. The models explored the effects of the between-speaker factors dialect, age and gender and included each phrase and its length as a source of both between- and within-speaker variation. The major findings are: (1) Wisconsin speakers speak significantly faster and produce shorter phrases than North Carolina speakers; (2) speech tempo changes across the lifespan, being fastest for individuals in their 40s; (3) men speak faster than women and this effect is not related to the length of phrases they produce. Articulation rate in reading was slower than in speaking and the effects of gender and age also differed in reading and spontaneous speech. The effects of dialect in reading remained the same, showing again that Wisconsin speakers had faster articulation rates than did North Carolina speakers.