Adding visual biofeedback to motor-based speech therapy improves /ɹ/ generalization in children with RSSD

This randomized controlled trial examined whether adding visual biofeedback to motor-based speech treatment improves generalization outcomes in children with residual speech sound disorders (RSSDs). 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, either with visual biofeedback (ultrasound or visual-acoustic) or without biofeedback.

The intervention incorporated motor learning principles, with task difficulty systematically adjusted to each child's performance. The primary outcome was /ɹ/ accuracy on untreated words before and after treatment, rated as correct or incorrect by lay listeners blinded to participant characteristics, treatment conditions, and time points.

A mixed-effects regression model revealed a statistically significant interaction between treatment type and time point. Both biofeedback and nonbiofeedback groups improved over time, but generalization to untreated words was significantly greater in the biofeedback condition than in the motor-based treatment alone. In a subanalysis comparing biofeedback modalities, ultrasound biofeedback produced greater generalization than visual-acoustic biofeedback, though this effect was strongest at one treatment site.

Safety, tolerability, adverse events, funding, and conflicts of interest were not reported in the abstract. A key limitation is that the advantage of ultrasound over visual-acoustic biofeedback was site-dependent, raising questions about generalizability across settings or clinicians.

For practice, these findings suggest that incorporating visual biofeedback into motor-based therapy can enhance generalization of accurate /ɹ/ production to untreated words in school-age children with RSSD. Clinicians should weigh the site-specific nature of the ultrasound-versus-visual-acoustic comparison when choosing a biofeedback modality.