The Relationship between Speech Accuracy and Linguistic Measures in Narrative Retells of Children with Speech Sound Disorders

Background: Speech and language are interconnected systems, and language disorder often co-occurs with childhood apraxia of speech (CAS) and non-CAS speech sound disorders (SSDs). Potential trade-off effects between speech and language in connected speech in children without overt language disorder have been less explored. Method: Story retell narratives from 24 children (aged 5;0-6;11 [years;months]) with CAS, non-CAS SSD, and typical development were analyzed in Systematic Analysis of Language Transcripts (SALT) regarding morphosyntactic complexity (mean length of C-unit in words [MLCU]), lexical diversity (moving-average type-token ratio [MATTR]), and linguistic accuracy (any linguistic error/bound morpheme omissions) and compared to 128 age-matched children from the SALT database. Linear and mixed-effects logistic regressions were performed with speech accuracy (percent phonemes correct [PPC]) and diagnostic group as predictors of the narrative variables. Results: PPC predicted all narrative variables. Poorer PPC was associated with lower MLCU and MATTR as well as a higher likelihood of linguistic errors. Group differences were only observed for the error variables. Comparison to the SALT database indicated that 13 of 16 children with CAS and SSD showed a higher-than-expected proportion of linguistic errors, with a small proportion explained by individual speech errors only. Conclusions: The high occurrence of linguistic errors, combined with the relationship between PPC and linguistic errors in children with CAS/SSD, suggests a trade-off between speech accuracy and language output. Longitudinal studies are needed to investigate whether children with SSDs without language disorder show more language difficulties over time as linguistic demands increase.