Lexical stress in childhood apraxia of speech: acoustic and kinematic findings.
Hailey C Kopera, Maria I Grigos
PMID 30744428WHAT IT FOUND
Children with childhood apraxia of speech showed less jaw movement timing contrast between stressed and unstressed syllables than typically developing peers, even when their speech sounded accurate.
Acoustic differences were not found.
Key findings
01Children with CAS produced significantly smaller jaw movement duration contrasts between stressed and unstressed syllables compared to typically developing children.
02There were no significant group differences in the use of acoustic cues (duration or fundamental frequency) to mark lexical stress.
03Children with speech delay did not differ significantly from either the CAS or typically developing groups in their use of jaw movement duration.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The sample size was very small (seven children with CAS), limiting the generalisability of the findings. The study analysed only one specific stress pattern (strong-weak) within a single nonsense word, so results may not apply to other stress structures. The study was retrospective, using data collected for a different project, which limited control over stimulus design. Intensity measures were excluded due to lack of a head-mounted microphone, potentially missing a relevant acoustic cue. The difference in jaw movement timing between children with CAS and those with speech delay was not statistically significant, despite descriptive trends.
Declared interests
The research was supported by the National Institutes of Health (N.I.H., Extramural). No other conflicts of interest are reported.
The easy way to misread this
Do not interpret the lack of acoustic differences as evidence that children with CAS have normal prosodic control. The study found significant kinematic differences in jaw movement timing that were not captured by acoustic measures alone.