Neuromuscular and sociolinguistic hypotheses were proposed to explore and account for the nature of individuals' idiosyncratic speech rates. One hundred subjects (50 males and 50 females) read the Farm Script passage at both habitual and maximum rates. FAST and SLOW subgroups of subjects were selected for both genders based on their overall speaking rates. The articulation rate data derived from 30 selected subjects (SLOW and FAST) revealed the following findings: (a) a significant linear regression function existed between the habitual and maximum rates, (b) significantly different maximum rates were found for the SLOW and the FAST groups, (c) roughly equivalent relative changes from habitual to maximum rate for both SLOW and FAST groups. No significant gender differences were found across different speech tasks and measures of speech rates. The weight of the evidence seems to suggest that neuromuscular constraints play a role in the determination of an individual's habitual speaking rate. Nevertheless, the study did not suggest that either neuromuscular hypotheses or sociolinguistic hypotheses alone can account for the control of individuals' speaking rates due to the unusual ability demonstrated by a few subjects in the SLOW group, to speak at very fast maximum rates.

This study provides a constructive replication of Tsao and Weismer (1997), showing a difference between slow and fast talkers with a new set of speech materials and in a new task. The findings appear to be consistent with a biological basis for intertalker rate differences.

The present study aimed to examine the size of the acoustic vowel space in talkers who had previously been identified as having slow and fast habitual speaking rates [Tsao, Y.-C. and Weismer, G. (1997) J. Speech Lang. Hear. Res. 40, 858-866]. Within talkers, it is fairly well known that faster speaking rates result in a compression of the vowel space relative to that measured for slower rates, so the current study was completed to determine if the same differences in the size of the vowel space occur across talkers who differ significantly in their habitual speaking rates. Results indicated that there was no difference in the average size of the vowel space for slow vs fast talkers, and no relationship across talkers between vowel duration and formant frequencies. One difference between the slow and fast talkers was in intertalker variability of the vowel spaces, which was clearly greater for the slow talkers, for both speaker sexes. Results are discussed relative to theories of speech production and vowel normalization in speech perception.

This study aims to find whether the acoustic vowel space reflect the habitual speaking rate of the speaker. The vowel space is defined as the area of the quadrilateral formed by the four corner vowels (i.e.,/i/,/æ/,/u/,/α) in the F1F2- 2 plane. The study compares the acoustic vowel space in the speech of habitually slow and fast talkers and further analyzes them by gender. In addition to the measurement of vowel duration and midpoint frequencies of F1 and F2, the F1/F2 vowel space areas were measured and compared across speakers. The results indicate substantial overlap in vowel space area functions between slow and fast talkers, though the slow speakers were found to have larger vowel spaces. Furthermore, large variability in vowel space area functions was noted among interspeakers in each group. Both F1 and F2 formant frequencies were found to be gender sensitive in consistence with the existing data. No predictive relation between vowel duration and formant frequencies was observed among speakers.

In a previous study [Tsao and Weismer, J. Speech Lang. Hear. Res. (1997)], it was demonstrated that interspeaker variation in habitual speaking rate is predictive of interspeaker variation in maximal speaking rate. Thus speakers who are habitually slow speakers do not seem to be able to produce as fast a maximum rate as speakers who are habitually fast. This finding was interpreted to mean that some component of interspeaker variation in habitual speaking rate reflects neurological predispositions, rather than (for example) voluntary ‘‘choices’’ of different rates. The present study explores the hypothesis that habitually slow and fast speakers may have differently sized acoustic vowel spaces. The hypothesis is derived from previous observations that within speakers, the size of the acoustic vowel space fluctuates with speaking rate. Results suggest that there is substantial overlap between the vowel spaces of habitually slow and fast speakers, but that the slow speakers do tend to have larger vowel spaces. [Work supported by NIH.]