The effect of vowel quality variations on stress-beat location

Abstract

This study examines the effect which vowel quality variations have upon the location of vowel onsets—indicators of stress-beat location—in rhythmically produced lists of monosyllables. Three talkers produced 120 sequences consisting of seven monosyllabic tokens of the form /s___t/. These token sequences were either homogeneous (identical components) or alternating (stimulus syllables alternated with the token “sight”). Talkers produced the sequences in both a metronome and nonmetronome condition. Analysis of the obtained results shows that vowel quality variations had a significant effect upon the location of the vowel onset. Regression analysis demonstrated that the differences in vowel onset-to-vowel onset intervals were significantly related to vowel duration differences between the tokens. There was also a significant difference between talkers in terms of the location of the vowel onsets, suggesting either the use of different production strategies or differential capabilities in doing the rhythmic task. No evidence of preboundary lengthening was obtained. These data support the suggestions [R. A. Fox and I. Lehiste, J. Acoust. Soc. Am. Suppl. 1 77, S54 (1985)] that the location of the “stress beat” is determined on the basis of the acoustic structure of the entire syllable, rather than strictly upon the articulatory onset of the vowel and that subjects in such a task do not necessarily impose a hierarchical structure on the syllabic sequences. Perceptual data relevant to the importance of vowel durations to the stress-beat location will also be presented.