Previous studies of coarticulatory patterns in children and adults have produced conflicting results, particularly with respect to anticipatory lingual coarticulation. This study used midsagittal tongue contour data from ultrasound imaging, in order to establish any differences between child and adult coarticulatory patterns, and to quantify the degree of variability in children's and adults' productions.
The participants were four adults and four typically developing children aged 6 to 9 years, all speakers of Standard Scottish English. The data were several fricative-vowel syllables, in a carrier phrase. Synchronised ultrasound and acoustic data were recorded using the Queen Margaret University ultrasound system. Extent of consonantal coarticulation and within-speaker variation in child and adult productions were compared according to the new ultrasound-based measure of coarticulation.
A significantly greater amount of anticipatory lingual coarticulation was found in children than in adults. Much within-group variability was observed in both groups. Within-speaker variability was significantly greater in children than in adults. These results are discussed in relation to previous studies. Possible reasons are suggested for some of the contradictions in the literature on child and adult coarticulation. Additionally, ways of measuring coarticulation dynamics from midsagittal ultrasound data are outlined and discussed.