Pre-boundary Lengthening Research Articles

The effect of vowel quality variations on stress-beat location

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.

Perception of sentence and paragraph boundaries in natural conversation

Subjects were presented with two versions (with and without semantic information) of a natural conversation and in each condition were asked to respond when they heard a sentence or paragraph boundary. Presence of semantic information resulted in increased numbers of both very quick and very slow responses. Sentence boundaries are cued by non-level intonation contours, laryngealization, pre-boundary lengthening, and presence of a pause, all unit-terminal phenomena; cues for paragraph boundaries both precede and follow a change in topic, reflecting the optional nature of topic changes in natural conversations.

PROPERTIES OF I-BOUNDARY LENGTHENING OF VOWELS IN ENGLISH AND SERBIAN

Phonological features which signal the right IP edge include boundary tones and pre-boundary lengthening. However, languages differ in the prominence of these features. While in English final information focus has significant F0 prominence on PWd immediately preceding I-boundary, Serbian primarily relies on durational cues to signal final information focus and, thus, the right IP edge. This research aims at analyzing the degree and scope of I-boundary lengthening in English and Serbian as well as examining whether there is a compensatory relation between F0 prominence and pre-boundary lengthening in these languages. The research is part of a larger-scale corpus study involving approximately one hour of read speech per language. Both English and Serbian speakers were professional newsreaders and the recordings were comparable in terms of articulation rate and recording quality. The acoustic analysis involved measuring the degree and scope of lengthening in trisyllabic PWds, which was done in the Praat programme (version 6.0.52). The results of the measurements were statistically analyzed. The results of the analysis primarily point to the differences in the scope of I-boundary lengthening in English and Serbian. While the scope of lengthening in Serbian affects the stressed vowel of IP-final PWd as well as all the vowels following it, English post-accented non-final unstressed vowels are skipped by this process. Accordingly, wider scope of lengthening might suggest slightly higher significance of this process in Serbian, which can further be interpreted as a compensation for low F0 prominence at the right IP edge in this language.