Developmental changes in the variability of tongue and lip movements during speech from childhood to adulthood: an EMA study.

This study investigated the developmental variability of lip and tongue movement in 48 children and adults. Motion of the tongue-tip, tongue-body and lower lip was recorded using electromagnetic articulography during productions of sentences containing /t/, /s/, /l/, /k/ and /p/. Four groups of speakers participated in the study: (1) aged 6-7 years; (2) 8-11 years; (3) 12-17 years; and (4) adults. The variation in distance, duration, speed, acceleration and deceleration of the articulators during single open-close speech movements was analysed, and the stability of multiple movement sequences was examined using the spatiotemporal index. The experimental findings revealed a gradual developmental progression from 6 years to adulthood. At adolescence, speakers continued to exhibit significantly more variable speech motor output compared to adult speakers. The observed developmental pattern suggests that attenuated, but important, changes in the speech motor system occurs from mid-childhood, through adolescence, to adulthood.

Temporal features of articulation from childhood to adolescence: an electropalatographic investigation.

This study was designed to investigate the development of articulatory timing from mid-childhood to late adolescence. Productions of sentences containing /t/, /l/, /s/, and /k/ were produced by 48 children and adults (aged 6-38 years) and captured using the Reading Electropalatography3 (EPG3) system. Mean duration of the sentences and the approach, closure/stable constriction, and release phases of consonant articulation were calculated. In addition, temporal coordination of lingual gestures and the intra-subject articulatory timing variation were investigated across the ages. Results reveal some distinct differences in duration and temporal coordination of lingual gestures between 6- to 7-year-olds and mature speakers, with continual refinement of articulatory control indicated into late adolescence. Differences in articulatory stability, in contrast, were not significant. The present findings may form a platform for development of a more descriptive model of motor speech development.

Physiologic development of tongue-jaw coordination from childhood to adulthood.

PURPOSE: This investigation aimed to examine the development of tongue-jaw coordination during speech from childhood to adolescence. METHOD: Electromagnetic articulography was used to track tongue and jaw motion in 48 children and adults (aged 6-38 years) during productions of /t/ and /k/ embedded in sentences. RESULTS: The coordinative organization of the tongue and jaw exhibited changes until the age of 8-11 years and continued to undergo refinement into late adolescence. The tongue-tip and tongue-body were observed to develop unique kinematic relations with the jaw. While tongue-tip movement became increasingly synchronized with jaw movement, tongue-body and jaw retained movement independence but developed a more consistent kinematic relation. CONCLUSION: The present results support the notion that speech motor development is nonuniform, with a refinement period from mid-childhood to late adolescence.

Electropalatographic assessment of tongue-to-palate contact patterns and variability in children, adolescents, and adults.

PURPOSE: To investigate the developmental time course of tongue-to-palate contact patterns during speech from childhood to adulthood using electropalatography (EPG) and a comprehensive profile of data analysis. METHOD: Tongue-to-palate contacts were recorded during productions of /t/, /l/, /s/, and /k/ in 48 children, adolescents and adults (aged 6-38 years) using the Reading Electropalatograph system. RESULTS: A protracted course of development for lingual control was indicated, with significant changes occurring until age 11 years; the adolescent period was in turn characterized by continual refinement of articulatory control. With maturity, a reduction in the amount of palatal contact and an anterior shift in the place of articulation was evident during anterior consonant productions, whereas the tongue-back-to-palate contact pattern became more consistent for the velar stop /k/. CONCLUSION: These results support that maturation of the speech motor system is nonuniform.