Language Skill Mediates the Relationship Between Language Load and Articulatory Variability in Children With Language and Speech Sound Disorders.

Purpose: The aim of the study was to investigate the relationship between language load and articulatory variability in children with language and speech sound disorders, including childhood apraxia of speech. Method: Forty-six children, ages 48-92 months, participated in the current study, including children with speech sound disorder, developmental language disorder (aka specific language impairment), childhood apraxia of speech, and typical development. Children imitated (low language load task) then retrieved (high language load task) agent + action phrases. Articulatory variability was quantified using speech kinematics. We assessed language status and speech status (typical vs. impaired) in relation to articulatory variability. Results: All children showed increased articulatory variability in the retrieval task compared with the imitation task. However, only children with language impairment showed a disproportionate increase in articulatory variability in the retrieval task relative to peers with typical language skills. Conclusion: Higher-level language processes affect lower-level speech motor control processes, and this relationship appears to be more strongly mediated by language than speech skill.