Numerical Model of Coarticulation

Abstract

The essential features of the coarticulation properties of Swedish dental stops in vowel-consonant-vowel contexts can be described by the formula s(x; t)=v(x; t)q-k(t)[c(x)--v(x; t)•wc(x), where x represents the longitudinal distance between lips and glottis and s(x; t) denotes the shape of the vocal tract at some instant of time, t, during the vowel-consonant-vowel utterance. The vowel component, v(x; t) is a linear combination of the three "extreme" shapes of the vowels/i/,/a/, and/u/with weights that vary as functions of time. The consonant is represented by c(x), an ideal target shape, and wc(x), a so-called coarticulation function. A time-varying factor k(t) represents the degree of excursion of the consonantal gesture. Vocal tract shapes measured from x-ray motion pictures of a set of Swedish vowel-consonant-vowel utterances compare well with shapes generated by the formula. This result is consistent with our earlier conclusions about coarticulation, viz., that the vowel and consonant gestures are largely independent at

Speech sound acquisition, coarticulation, and rate effects in a neural network model of speech production.

“…Ohman (1966Ohman ( , 1967 hypothesized that this is possible because vowels and consonants use largely independent subsets of the vocal tract musculature. Fowler (1980) repeated this sentiment, hypothesizing that different coordinative structures exist for the two sound types.…”

“…In the coproduction model (e.g., Ohman, 1966Ohman, , 1967Fowler, 1980;Saltzman and Munhall, 1989), vowel and consonant gestures have fixed time courses, but these time courses can be overlapped in time with the time courses of neighboring gestures. Ohman (1966Ohman ( , 1967 hypothesized that this is possible because vowels and consonants use largely independent subsets of the vocal tract musculature.…”

A wavelet model for vocalic speech coarticulation

“…In his spectrographic studies on vowel-consonant-vowel /VCV/ utterances, Ohman (1966;1967) demonstrated a number of mutual coarticulatory effects which occur within the vowel-consonant pair. He examined in particular the formant transition interval between vowel and consonant, namely, the transitions between /VC/ and between /CV/.…”

Susceptibility of a stop consonant to adaptation on a speech-nonspeech continuum: Further evidence against feature detectors in speech perception

“…Unlike the categorical consonants, vowels are perceived more continuously (Fry, Abramson, Eimas, & Liberman, 1962); vowels do not exhibit a rightear superiority when presented dichotically, though consonants do (Studdert-Kennedy & Shankweiler, 1970); memory processes for consonants and vowels differ (Crowder, 1971;Pisoni, 1975), as do their perceived psychophysical scales (Vinegrad, 1972;Perey & Pisoni, Note 2). Vowels and consonants also appear to require different types of motor acts (Fowler, Rubin, Remez, & Turvey, in press;Ohman, 1966Ohman, , 1967Perkell, 1969). In short, the precondition of the earlier test of Remez (1979), that one of the continuum endpoints be speech and the other not, may not have been met.…”