Ultrasound analysis of tongue shape over time during remediation of velar fronting in Persistent Speech Sound Disorder: Case study

Abstract

Ultrasound imaging of the tongue is becoming increasingly popular in the field of Speech and Language Therapy for research, diagnostic and therapeutic purposes. Despite the growing body of evidence from recent studies to support the efficacy of ultrasound as visual biofeedback (U-VBF) in the remediation of persistent Speech Sound Disorders, they report mainly qualitative results of ultrasound data. This study uses both qualitative and quantitative measures to analyse ultrasound tongue images, while comparing tongue contours for velar and alveolar speech sounds in one child with persistent velar fronting. Perceptual analysis of acoustic data allowed the analyst determine perceptual categorical neutralisations of speech sounds to be recorded at various time points during (U-VBF) intervention. Ultrasound analysis allowed annotated tongue contours to be superimposed dynamically to identify differences in tongue shape and height over time when comparing contrastive speech sounds. Furthermore, it was hypothesised that undetectable error types in tongue shape for perceptually neutralised velar and alveolar target sounds would be identified using quantitative measures. To quantify the difference in tongue-height over time the built-in statistical difference function in Articulate Advanced Software (AAA) was used. Results show no evidence to suggest error types in tongue shape that differ from neutralisations that would otherwise be detected perceptually at any time point analysed in this study. Evidence does support increased acquisition of velar targets in various word positions at multiple time points progressively. Ultimately, this study offers evidence to contribute towards understanding the efficacy of U-VBF as a therapeutic technique in the remediation of persistent velar fronting.