Rhotic Generalization Is More Rapid in Biofeedback Than Motor-Based Treatment for Residual Speech Sound Disorder: Secondary Outcomes of a Randomized Controlled Trial.

PURPOSE: This study examined the effects of visual biofeedback approaches and nonbiofeedback motor-based treatment on generalization outcomes following speech therapy for children with residual speech sound disorders (RSSDs).

METHOD: A total of 108 children aged 9-15 years with RSSD affecting American English /ɹ/ were randomly assigned to receive 19 motor-based speech treatment sessions, with or without visual biofeedback (divided into ultrasound or visual-acoustic biofeedback). The treatment included practice designed to implement several motor learning principles, with task difficulty systematically adjusted based on the child's performance. Children's /ɹ/ accuracy on untreated words before and after treatment was rated as correct or incorrect by lay listeners who were blinded to participant characteristics, treatment conditions, and time points.

RESULTS

The mixed-effects regression model revealed a statistically significant interaction between treatment type and time point. Specifically, both the biofeedback and nonbiofeedback motor-based treatment groups made progress over time, but the amount of generalization to untreated words was significantly greater in the biofeedback condition than in the motor-based treatment. In a subanalysis comparing biofeedback types, greater generalization was observed following ultrasound biofeedback than visual-acoustic biofeedback, although this effect was strongest at one treatment site.

DISCUSSION: This randomized controlled trial found that adding biofeedback to motor-based treatment can increase the rate of accurate production of the American English /ɹ/ in untreated words.