Does Speech Emerge From Earlier Appearing Oral Motor Behaviors?

Abstract

This investigation was designed to quantify the coordinative organization of mandibular muscles in toddlers during speech and nonspeech behaviors. Seven 15-month-olds were observed during spontaneous production of chewing, sucking, babbling, and speech. Comparison of mandibular coordination across these behaviors revealed that, even for children in the earliest stages of true word production, coordination was quite different from that observed for other behaviors. Production of true words was predominantly characterized by relatively stronger coupling among all mandibular muscles compared with earlier-emerging chewing and sucking. Variegated babbling exhibited stronger coupling than reduplicated babbling, as well as chewing and sucking. The finding of coupled activation among mandibular antagonists during speech paralleled earlier comparisons of adult speech and nonspeech behaviors (Moore, Smith, & Ringel, 1988) and did not support the suggestion that speech coordination emerges from earlier appearing oral motor behaviors. Keywordsspeech; development; motor control; mandible; human A persistent question in our understanding of the coordinative framework of speech production is the relationship of speech to other oral motor behaviors (Moore, Smith, & Ringel, 1988;Ostry, Feltham, & Munhall, 1984;Ostry & Munhall, 1994). Although recent investigations have provided strong support for the existence of separate and distinct mechanisms for speech and nonspeech coordination in adults (Moore et al., 1988), empirical physiologic studies of speech development are lacking. This lack of evidence leaves in doubt the essential foundations of speech motor control.Two lines of reasoning can be taken to address the coordinative framework of speech during the early stages of development. The first draws on mechanisms of pattern generation, which have been directly observed in animals (see Grillner, 1981), as well as dynamical systems theory (e.g., Fentress, 1976;Kent & Hodge, 1990;Thelen & Cooke, 1987;Thelen & Fisher, 1983;Thelen, Skala, & Kelso, 1987; Thelen & Urich, 1991). A dynamic pattern perspective might suggest that speech movements emerge gradually through an interaction of context (i.e., external conditions) with intrinsically generated patterns stemming from the rhythmic movements of sucking, chewing, reduplicated babbling, and variegated babbling. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptAn alternative approach holds that speech develops independent of extant behaviors, emerging as a new and unique motor skill. Support for this position is drawn directly from observations of babbling rhythmicity (see summary by Kent, Mitchell, & Sancier, 1991) and further relies on findings that the coordinative organization of mature speech is distinct from that of any of the postulated precursors (Moore et al., 1988;Ostry & Munhall, 1994). The established orofacial coordination available to children from these behaviors does not appear to be well suited to speech. For example, kinematic and po...

The development of oral motor control and language

“…Previous studies of the link between oral motor skills and language have tended to look at simple movements more closely resembling eating movements (Moore & Ruark, 1996), or fast repeated movements (Dworkin & Culatta, 1985), neither of which seem to have a relationship with language development and disorders in these two studies. Our data suggest that more difficult oral movements are more closely related to language skills, possibly because they are more speech-like.…”

“…There is in fact very little data on this link. Moore and Ruark (Moore & Ruark, 1996) used EMG recordings to examine the coordination of activity in feeding behaviour and speech motor behaviour, and suggested that these were not linked. However, the types of motor activity examined in the non-speech category in this study were mainly those involving a single set of muscles -opening and closing the mouth, chewing etc.…”

Development of Chewing in Children From 12 to 48 Months: Longitudinal Study of EMG Patterns

“…This concern was addressed in several ways in this study, which is one of a series of investigations of these children (e.g., Moore and Ruark 1996). First, the distance between electrode pairs was large compared with distance within electrode pairs (e.g., 0.5-cm interelectrode distance for ABD electrode pairs, which were ~5 cm from the nearest masseter pair) somewhat reducing volume conduction effects.…”

Diagnostic markers for child speech‐sound disorders: introductory comments

“…There has been, however, a trend since the mid-1990s toward certain claims about the neurodevelopmental substrates of speech-sound disorders. Notably in the USA, for example, some speech treatment has been based on the hypothesis that some children have significant deficits in variables such as 'oral sensation', 'oral-motor development', 'sensory-motor integration' and other currently unsupported explanatory constructs (see evaluative reviews by Moore and Ruark, 1996;Weismer, 1997;Forrest, 2002;Strand, Hodge and Forrest, 2002). We, too, suggest that such etiological claims lack the research support needed to recommend oral-motor therapy as a necessary or sufficient treatment component for children with common speech delay.…”