Articulatory, Segmental, and Prosodic Characteristics in Children with Speech Sound Disorders
The purpose of this project was to investigate how language, phonological, and speech motor skills interact in children diagnosed with what are traditionally viewed as language (i.e., specific language impairment), phonological (i.e., speech sound disorder), and motor speech (i.e., childhood apraxia of speech) disorders. Although these three groups are treated as unique diagnostic categories, children with specific language impairment and childhood apraxia of speech frequently display deficits across language, phonological, and speech motor domains. The goal was to address whether these domains are independent or whether interactivity is observed across groups in a systematic manner. Specifically, this project investigated whether articulatory, segmental, and prosodic features of speech production (features that are typically associated with childhood apraxia of speech) differentiate motor-based from language-based speech sound disorders. Forty-six children, ranging in age from 48–92 months, participated in this project. Children from four group were recruited; those with typical development (n = 14), speech sound disorder (n = 14), specific language impairment (n = 12), and childhood apraxia of speech (n = 6). All children completed a diagnostic battery to determine group classification and three experimental tasks designed to assess articulatory, segmental, and prosodic speech features. Transcription measures of segmental accuracy and variability and speech kinematic measures of spatiotemporal movement patterning were compared across the four groups. The transcription results generally patterned with behavioral features traditionally associated with speech sound disorder, specific language impairment, and childhood apraxia of speech. Children with presumed motor-based disorders (childhood apraxia of speech) were not differentiated from children with language-based disorders (specific language impairment) based on articulatory variability or prosodic errors. In a language retrieval context, children with language impairment (those with specific language impairment and with childhood apraxia of speech) showed a disproportionate disruption in articulatory movement patterning compared to peers with typical language skills. In the nonword repetition task, children with speech impairment showed higher articulatory variability than peers with typical speech skills. Increased length (3- versus 2-syllables) resulted in lower segmental accuracy and higher segmental and articulatory variability across all four groups. The results of this project suggest that articulatory variability does not differentiate motor-based from language-based communication disorders. Rather, spatiotemporal organization of speech movements is sensitive to language processing demands. Increased linguistic load (retrieving versus imitating phrases) and increased length (imitating 3- versus 2-syllable nonwords) affects segmental accuracy and segmental and articulatory variability measures. Children do not show a hierarchical and encapsulated language production system. Interactions are observed across processing stages, and in the current study some interactions were mediated by language ability.
Goffman, Purdue University.
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