On the sufficiency of compound target specification of isolated vowels and vowels in /bVb/ syllables

Abstract

It has been suggested [e.g., Strange et al., J. Acoust. Soc. Am. 74, 695-705 (1983); Verbrugge and Rakerd, Language Speech 29, 39-57 (1986)] that the temporal margins of vowels in consonantal contexts, consisting mainly of the rapid CV and VC transitions of CVC's, contain dynamic cues to vowel identity that are not available in isolated vowels and that may be perceptually superior in some circumstances to cues which are inherent to the vowels proper. However, this study shows that vowel-inherent formant targets and cues to vowel-inherent spectral change (measured from nucleus to offglide sections of the vowel itself) persist in the margins of /bVb/ syllables, confirming a hypothesis of Nearey and Assmann [J. Acoust. Soc. Am. 80, 1297-1308 (1986)]. Experiments were conducted to test whether listeners might be using such vowel-inherent, rather than coarticulatory information to identify the vowels. In the first experiment, perceptual tests using "hybrid silent center" syllables (i.e., syllables which contain only brief initial and final portions of the original syllable, and in which speaker identity changes from the initial to the final portion) show that listeners' error rates and confusion matrices for vowels in /bVb/ syllables are very similar to those for isolated vowels. These results suggest that listeners are using essentially the same type of information in essentially the same way to identify both kinds of stimuli. Statistical pattern recognition models confirm the relative robustness of nucleus and vocalic offglide cues and can predict reasonably well listeners' error patterns in all experimental conditions, though performance for /bVb/ syllables is somewhat worse than for isolated vowels. The second experiment involves the use of simplified synthetic stimuli, lacking consonantal transitions, which are shown to provide information that is nearly equivalent phonetically to that of the natural silent center /bVb/ syllables (from which the target measurements were extracted). Although no conclusions are drawn about other contexts, for speakers of Western Canadian English coarticulatory cues appear to play at best a minor role in the perception of vowels in /bVb/ context, while vowel-inherent factors dominate listeners' perception.

Speeded detection of vowels: A cross-linguistic study

“…As summarized by recent contributions to this debate (e.g., Andruski & Nearey, 1992;Nearey, 1989;Rosner & Pickering, 1994;Strange, 1989a), current theories contrast the extraction of underlying target values via compensation for contextual effects (e.g., Kuwabara, 1985;Miller, 1989) with perception of dynamic specification of vowel identity, for example, in transitional information (Strange, 1989b;Verbrugge & Rakerd, 1986) or in vowel-inherent spectral change (Nearey & Assmann, 1986). We do not claim that an on-line task with natural vowel tokens addresses the same issues as arise in these debates.…”

“…In the case of vowels, listeners may be asked to classify a sound as a member of a particular category (e.g., Andruski & Nearey, 1992;Strange, 1989b); or it may be determined whether they can discriminate between two sounds belonging to the same or different categories (e.g., Gottfried, Jenkins, & Strange, 1985;Schouten & van Hessen, 1992); or detection thresholds for different sound categories may be measured as a function ofcontext (e.g., Rakerd, Verbrugge, & Shankweiler, 1984) or at varying intensity levels (e.g., Kewley-Port, 1991). These tasks have the valuable property offorcing a response from the subject, even ifit is only a best guess.…”

Cross-dialectal variation in formant dynamics of American English vowels

“…Dynamic variations at the vowel target do exist in naturally produced nominal monophthongs and have been found in selective acoustic studies of American, Canadian, and Australian English vowels ͑e.g., Andruski and Nearey, 1992;Hillenbrand et al, 1995;Watson and Harrington, 1999͒. Yet, there is no acoustic evidence that vowel-inherent spectral change may actually vary systematically across geographic regions of the country and that the use of time-varying features may be a subject to regional variation.…”

Vowel identification by younger and older listeners: Relative effectiveness of vowel edges and vowel centers

“…It is well established that normal-hearing native listeners can identify vowels in CVC syllables on the basis of either the dynamic formant transitions that occur at the edges of the vowels, or the quasi steady-state formants that occur at the centers of the vowels, at least when the entire transitions or centers are provided Jenkins et al, 1983;Andruski and Neary, 1992). However, less is known about how well these listeners can identify vowels when only a portion of the formant transition or vowel center is available.…”