Perceptual and Acoustic Effects of Dual-Focus Speech Treatment in Children With Dysarthria

Purpose: Children with dysarthria secondary to cerebral palsy may experience reduced speech intelligibility and diminished communicative participation. However, minimal research has been conducted examining the outcomes of behavioral speech treatments in this population. This study examined the effect of Speech Intelligibility Treatment (SIT), a dual-focus speech treatment targeting increased articulatory excursion and vocal intensity, on intelligibility of narrative speech, speech acoustics, and communicative participation in children with dysarthria. Method: American English-speaking children with dysarthria (n = 17) received SIT in a 3-week summer camplike setting at Columbia University. SIT follows motor-learning principles to train the child-friendly, dual-focus strategy, "Speak with your big mouth and strong voice." Children produced a story narrative at baseline, immediate posttreatment (POST), and at 6-week follow-up (FUP). Outcomes were examined via blinded listener ratings of ease of understanding (n = 108 adult listeners), acoustic analyses, and questionnaires focused on communicative participation. Results: SIT resulted in significant increases in ease of understanding at POST, that were maintained at FUP. There were no significant changes to vocal intensity, speech rate, or vowel spectral characteristics, with the exception of an increase in second formant difference between vowels following SIT. Significantly enhanced communicative participation was evident at POST and FUP. Considerable variability in response to SIT was observed between children. Conclusions: Dual-focus treatment shows promise for improving intelligibility and communicative participation in children with dysarthria, although responses to treatment vary considerably across children. Possible mechanisms underlying the intelligibility gains, enhanced communicative participation, and variability in treatment effects are discussed.