An Electromygraphic-Cineflourographic Investigation of Velar Function During Normal Speech Production

Abstract

Impetus for this study was provided by a concept of palatal function described by M011 and Shriner (23) which suggests that, although palatal movement and position during the production of non—nasal sounds varies predictably in relation to such factors as phone type, duration, and consonantal context, the underlying neuromuscular activity is essentially invariant. More specifically, two levels of palatal muscular contraction are hypothesized: a) a relatively high level for the production of all non-nasal phones which require complete or nearly complete velopharyngeal closure, and 2) a relatively low level presumed to be characteristic of the production of nasal sounds and phrasing breaks when the velopharyngeal port is relatively open. In the case of prolonged vowels the variations in palatal position that occur in predictable association with differences in tongue height are attributed to constraints on palatal movement due to anatomical interconnection (for example, connections to the tongue via the palato— glossus muscle). Reduced palatal elevation in rapidly repeated nasal consonant vowel syllables (which require alternate opening and closing of the velopharyngeal port) is explained as the inevitable result of the inertia of the palate which dictates that full elevation of the palate cannot be attained unless a certain minimum time is available. The data showing that palatal elevation may vary depending on the contextually adjacent consonants, or whether the vowel stands alone without preceding or following consonants, are also explained as a mechanico—inertial effect. This hypothesis is based upon more generalized theories of articulation which have been suggested by such investigators as Liberman, Cooper, Harris, and MacNeilage (14), Lindblom (15, 16), and Stevens and House (27). Although the import of these earlier theories is reCOgnized, the present investigation will be concerned only with Moll and Shriner's applications of them to palatal function.