The Physiologic Development of Speech Motor Control

Abstract

This investigation was designed to describe the development of lip and jaw coordination during speech and to evaluate the potential influence of speech motor development on phonologic development. Productions of syllables containing bilabial consonants were observed from speakers in four age groups (i.e., 1-year-olds, 2-year-olds, 6-year-olds, and young adults). A video-based movement tracking system was used to transduce movement of the upper lip, lower lip, and jaw. The coordinative organization of these articulatory gestures was shown to change dramatically during the first several years of life and to continue to undergo refinement past age 6. The present results are consistent with three primary phases in the development of lip and jaw coordination for speech: integration, differentiation, and refinement. Each of these developmental processes entails the existence of distinct coordinative constraints on early articulatory movement. It is suggested that these constraints will have predictable consequences for the sequence of phonologic development.

Coordinative Organization of Lingual Propulsion during the Normal Adult Swallow

“…A cross-correlation analysis, as described previously by Green et al [17], was used to quantify the spatiotemporal characteristics of lingual propulsion during swallowing. Peak coefficients (negative or positive) and their associated lags were derived from each cross-correlation function, which were computed between the treated displacement traces of the following tongue pellet pairs: T1×T2, T2×T3, T3×T4, T1×T3, T2×T4, and T1×T4.…”

Spontaneous facial motility in infancy: A 3D kinematic analysis

“…Similarly, movements of the upper and lower lips also appear to be highly coupled in early childhood (Green et al, 2000). This very restrictive form of lip coordination may limit the sound producing capabilities of young children and suggest that further gains in speech will require an increase in the ability to move the upper and lower lips independently (Green et al, 2000).…”

“…Specifically, coordinated muscle activity may not always result in well-controlled movements in early development because infants are learning to manage interactions between the active forces generated by their muscles and the passive forces of their musculoskeletal system (Green et al, 1997(Green et al, , 2000.…”

“…The details of this analysis have been presented elsewhere (Green et al, 2000). Peak coefficients (negative or positive) and their associated lags were derived from the cross-correlation functions computed between the Euclidean distance time-histories of six marker pairs: CR×CL, CR×LL, UL×LL, UL×CR, ER×EL, and ER×LL.…”

“…Several investigators have suggested that spontaneous oral movements in the fetus emerge in the following order: jaw opening, jaw closing, tongue movement, and lip movement (see Herring, 1985;Humphrey, 1970Humphrey, , 1971. Jaw opening and closing are also primary features of babble and early speech (Green, Moore, Higashikawa, & Steeve, 2000).…”