Numerical Model of Coarticulation

Sven Öhman

The Journal of the Acoustical Society of America · 1967 · 291 citations · 0 references

Concepts

TL;DR

Coarticulation of Swedish dental stops in vowel‑consonant‑vowel contexts can be modeled by a formula that combines vowel shapes, a consonant target shape, and a time‑varying coarticulation function based on lip‑glottis distance. X‑ray measurements of Swedish VCV utterances match the model’s predicted vocal‑tract shapes, supporting the view that vowel and consonant gestures are largely neurally independent.

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; l)+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 the level of neural instructions.