Exploring perception of coarticulatory cues in childhood apraxia of speech and residual speech sound disorders: A pilot study.

INTRODUCTION: Children with childhood apraxia of speech (CAS) exhibit speech production deficits beyond segmental errors, including atypical coarticulation. Broadly, children with speech sound disorders (SSD) also exhibit weaknesses in speech perception, which may directly relate to specific production difficulties. This study examined differences in categorical perception among children with CAS, residual SSD affecting /ɹ/ (rSSD), and typical speech (TD). We hypothesized that children with CAS would demonstrate weaker performance on a task requiring perception of coarticulatory cues-a defining weakness in their speech production-but perform similarly to rSSD peers on a segmental task.

METHODS: This study was designed as an exploratory pilot project, embedded in the baseline assessment of a series of speech treatment studies. Participants included 96 children (ages 8;0-15;11), 44 CAS, 39 rSSD, and 13 TD. In the segmental perception task, participants judged stimuli from a 5-step /al/ - /aɹ/ continuum. In the second task, /al/ and /aɹ/ endpoints were prefixed to a 5-step /ga/-/da/ continuum, creating /al/ (/alga/ - /alda/) and /aɹ/ (/aɹga/ - /aɹda/) conditions. Compensation for coarticulation was assessed at an ambiguous step, where listeners were expected to perceive /g/ after /al/ or /d/ after /aɹ/.

RESULTS & CONCLUSIONS: Compensation for coarticulation was significantly weaker among children with CAS, who also demonstrated less reliable perception of /ga/ - /da/ endpoints and segmental perception weaknesses on the /al/ - /aɹ/ task not seen in rSSD or TD. Findings contribute an initial characterization of perceptual compensation for coarticulation in children with CAS. Results highlight performance differences based on underlying SSD subtype and may be clinically useful for future development of diagnostic tools that bypass verbal output limitations.