The perception and production of rhyme in normal and developmentally apraxic children.

The phonological competence of four children, aged 5-7 years old, who demonstrated a cluster of symptoms consistent with a diagnosis of developmental apraxia of speech (DAS), was contrasted to that of four normal children. Four rhyming tasks were used to assess the ability of the children to both spontaneously generate rhyming words to targets and to judge the (in)appropriateness of a rhyme in both a word series and forced-choice word pairs. The DAS children revealed a severe deficit in rhyming ability across all tasks and had rhyming abilities markedly inferior to those shown by normal children. The rhyming results were interpreted as possibly indicative of an impoverishment of an internalized phonemic representation system, which precludes accessing and evoking the needed sound image for the vowel + coda for a rhyme. These results, while preliminary in nature, lend support to a conceptualization of DAS as a fundamental disorder of the segmental phonological level of language that impacts on all hierarchically relevant language components. The hypothesis that the underlying etiology of DAS is a developmental dysmorphology of the neural substrates that mediate such basic phonological representational structure is discussed.