Impact of sentence length and phonetic complexity on intelligibility of 5-year-old children with cerebral palsy.

Reduced speech intelligibility is a barrier to effective communication for many children with cerebral palsy (CP). Many variables may impact intelligibility, yet little research attention has sought to quantify these variables. This study examined the influence of sentence characteristics on intelligibility in two groups of children with CP (those with and without dysarthria) and typically-developing children. Questions addressed effects of sentence length on transcription intelligibility among groups; effects of phonetic complexity on intelligibility; and differences in the relationship between sentence characteristics and intelligibility across individual children with dysarthria. Speech samples varying in length from 2-7 words were elicited from 16 children with CP (mean age 59.6 months) and eight typically-developing children (mean age = 59.8 months). One hundred and nineteen naïve listeners made orthographic transcriptions of the children's sentence productions. Sentence length and phonetic complexity affected intelligibility for all groups of children, but had a greater impact on intelligibility for children with dysarthria than those without speech motor impairment. Variable relationships between sentence characteristics and intelligibility were found across individual children with dysarthria. Results suggest that reducing both the length and phonetic complexity of utterances may enhance intelligibility for children with dysarthria. However, there may be important individual differences in the impact of one or both types of sentence characteristics. This highlights the importance of considering individual speech motor profiles when deciding on treatment strategies.