ACOUSTIC MEASURES OF TEMPORAL INTERVALS ACROSS SPEAKING RATES - VARIABILITY OF SYLLABLE-LEVEL AND PHRASE-LEVEL RELATIVE TIMING

It has been suggested previously that at least some levels of the temp oral organization For speech production are characterized by proportio nal timing. The proportional timing model maintains that the duration of temporal intervals within a sequence would remain proportionally in variant across changes in overall duration of the sequence. In order t o test this hypothesis for the acoustic level of speech production, 18 women produced three trials of the utterance ''Buy Bobby a poppy'' at each of three speaking rates (i.e., slow, normal, fast). Acoustically derived temporal intervals were paired to form ratios reflecting eith er syllable-level or phrase-level relative timing. Findings indicated that ratios of temporal intervals;at both the syllable-level and phras e-level did not remain invariant across speaking rates. Rather, statis tically significant changes in the relative duration of both types of intervals were observed as a function of overall rate of production. F or most of the obtained ratios, the direction of these changes was hig hly consistent across individual subjects.