Abstract:

This examination of speech motor control in phonologically disordered children adapted a paradigm that has been used in the dysarthria literature [Weismer et al., J. Acoust. Soc. Am. 91, 1085--1098 (1992)]. Six preschool-aged children with phonological disorders, six age controls, and six adults repeated the phrases ``baby dog'' and ``good baby'' at normal and fast rates. F2 tracks of the fast rate tokens were processed using an in-house algorithm to calculate the transition slope in Hz/ms. For the alveolar and velar stops (but not for the labial stops) the F2 slope distributions for the typically developing children were quite similar to those of the adults, and both differed from the children with phonological disorders in showing smaller slope values. The phonologically disordered children had faster movements than either their age controls or adults, but only in the sequences where the tongue--jaw complex was harnessed for the consonant as well as for the contiguous vowel. This pattern suggests that the phonologically disordered children are using a faster, more ballistic gesture for lowering the tongue--jaw complex for all three stop places of articulation, while the typically developing children and adults use this strategy only after a labial closure.