Spatial and temporal lingual coarticulation and motor control in preadolescents

Abstract

Purpose: Coarticulation and lingual kinematics were compared in preadolescents and adults, in order to establish whether preadolescents had a greater degree of random variability in tongue posture and whether their patterns of lingual coarticulation differed from those of adults.

Method: High-speed ultrasound tongue contour data synchronised with the acoustic signal were recorded from 15 children aged between 10 and 12 years old, and 15 adults. Tongue shape contours were analysed at nine normalised time-points during the fricative phase of schwa-fricative-/a/ and schwa-fricative-/i/ sequences with the consonants /s/ and /ʃ/.

Results: There was no significant age-related difference in random variability. Where a significant vowel effect occurred, the amount of coarticulation was similar in the two groups. However, the onset of the coarticulatory effect on preadolescent /ʃ/ was significantly later than on preadolescent /s/, and also later than on adult /s/ and /ʃ/.

Conclusions: Preadolescents have adult-like precision of tongue control and adult-like anticipatory lingual coarticulation with respect to spatial characteristics of tongue posture. However, there remains some immaturity in the motor programming of certain complex tongue movements.