Enhancing Intervention for Residual Rhotic Errors Via App-Delivered Biofeedback: A Case Study

Abstract

Purpose: Recent research suggests that visual-acoustic biofeedback can be an effective treatment for residual speech errors, but adoption remains limited due to barriers including high cost and lack of familiarity with the technology. This case study reports results from the first participant to complete a course of visual-acoustic biofeedback using a not-for-profit iOS app, Speech Therapist's App for /r/ Treatment.

Method: App-based biofeedback treatment for rhotic misarticulation was provided in weekly 30-min sessions for 20 weeks. Within-treatment progress was documented using clinician perceptual ratings and acoustic measures. Generalization gains were assessed using acoustic measures of word probes elicited during baseline, treatment, and maintenance sessions.

Results: Both clinician ratings and acoustic measures indicated that the participant significantly improved her rhotic production accuracy in trials elicited during treatment sessions. However, these gains did not transfer to generalization probes.

Conclusions: This study provides a proof-of-concept demonstration that app-based biofeedback is a viable alternative to costlier dedicated systems. Generalization of gains to contexts without biofeedback remains a challenge that requires further study. App-delivered biofeedback could enable clinician-research partnerships that would strengthen the evidence base while providing enhanced treatment for children with residual rhotic errors.

Supplemental material: https://doi.org/10.23641/asha.5116318.

Figures

Figure 1.

Formant frequencies represented as peaks of a linear predictive coding spectral display in the Speech Therapist's App for /r/ Treatment (staRt) app. The third formant (F3), which is targeted in rhotic treatment, is labeled.

Figure 2.

Still frame from the Speech Therapist's App for /r/ Treatment (staRt) introductory tutorial. Notable features include the side navigation panel, the biofeedback display, the starfish character, and sand dollars representing the user's progress through the tutorial.

Figure 3.

Points represent percentages of rhotic syllables/words rated perceptually accurate in treatment trials, reflecting scores assigned in real time by treating clinician. Shaded area represents 95% confidence interval around best-fit loess curve (line).

Figure 4.

Mean F3–F2 distance in rhotic syllables/words in treatment trials. Bars represent 95% confidence interval around the mean.

Figure 5.

Mean F3–F2 distance in /ɝ, ɑɚ, ɔɚ/ words produced in baseline, within-treatment, and maintenance probe measures. Bars represent 95% confidence intervals. Dotted line represents mean F3–F2 distance across the three baseline sessions.