Relationship Between Prosody and Intelligibility in Children with Dysarthria

Exaggerated and redundant prosodic cue use has been noted among adults with dysarthria secondary to cerebral palsy (CP) (Patel, 2004; van Doorn & Sheard, 2001). A possible explanation may be that speakers heighten prosodic contrasts to increase intelligibility. The current work examined whether children with dysarthria due to CP also produce exaggerated prosodic contours and if so, how prosodic cue use in these speakers impacts intelligibility. Acoustic analyses were conducted on a previously collected dataset of 2-7 word utterances produced by fourteen children with CP (7 with dysarthria and 7 without) (Hustad, Gorton & Lee, 2010). The dataset also included sentence-level transcriptions obtained from five listeners per speaker. Word intelligibility scores were derived from these transcripts and used to determine whether prosodic modulation differed for words with high versus low intelligibility. Although mean fundamental frequency (F0) and intensity range were similar across groups, words produced by children with dysarthria were slower and more variable in F0 than the group without dysarthria. Moreover, intelligibility decreased when children with dysarthria increased F0 and duration beyond the range used by children without dysarthria. Thus findings suggest that interventions targeting appropriate prosody may be beneficial in improving intelligibility in children with dysarthria and CP.