staRt: Enhancing Speech Treatment With Smartphone-delivered Biofeedback (staRt)

National Institutes of Health (NIH), National Institute on Deafness and Other Communication Disorders (NIDCD)

Previous research suggests that biofeedback can outperform traditional interventions for RSE, but no controlled studies have tested this hypothesis in the context of app-delivered biofeedback. The objective of this aim is to use the staRt app to test our working hypothesis that speakers will make larger gains in /r/ accuracy when app-based treatment incorporates biofeedback, compared to a non-biofeedback condition. With a network of cooperating SLPs, this project will recruit 15 children with /r/ misarticulation to receive 8 weeks of intervention using staRt. Individual sessions will be randomly assigned to include or exclude the visual biofeedback display. Randomization tests will be used to evaluate, for each individual, whether larger increments of change are associated with biofeedback and non-biofeedback sessions.

Children with /r/ misarticulation will receive 16 sessions/8 weeks of intervention using staRt. Individual sessions will be randomly assigned to include the visual biofeedback display (visual-acoustic biofeedback treatment) or exclude it (traditional treatment). Participants will receive an equal number of sessions (8) of each type.

Acoustic measures will be obtained by research assistants blinded to the treatment condition assigned for each session.

Traditional articulation treatment involves providing auditory models and verbal descriptions of correct articulator placement, then cueing repetitive motor practice. Images and diagrams of the vocal tract can be used as visual aids; however, no real-time visual display of articulatory or acoustic information will be made available. Knowledge of performance feedback could describe either the desired articulator placement or the auditory quality of the target sound.

In visual-acoustic biofeedback treatment, the elements of traditional treatment (auditory models and verbal descriptions of articulator placement) are enhanced with a dynamic display of the speech signal in the form of the real-time LPC (Linear Predictive Coding) spectrum generated by the staRt app. Because correct vs incorrect productions of /r/ contrast acoustically in the frequency of the third formant (F3), participants will be cued to make their real-time LPC spectrum match a visual target characterized by a low F3 frequency. They will be encouraged to attend to the visual display while adjusting the placement of their articulators and observing how those adjustments impact F3. Knowledge of performance feedback will typically involve reference to the location of the third peak or 'bump' on the visual display.

F3-F2 Distance, an Acoustic Measure That Correlates With Perceptual Accuracy of /r/, Measured From /r/ Sounds Produced in Treatment Sessions.

From recordings of words containing /r/ produced during treatment sessions, the sound /r/ was flagged for measurement and the first three formants (F1, F2, F3) were extracted from the center of the /r/ interval. The distance between the second and third formants (F3-F2) was used as the index of rhoticity. F3-F2 is small in perceptually accurate /r/, larger values indicate lower accuracy. Summary statistics report the mean and standard deviation of normalized F3-F2 distance for each treatment condition, pooled across participants and sessions. A two-tailed paired-samples t-test (superiority criterion) was used to compare mean F3-F2 distance for each treatment condition across subjects.

F3-F2 distance was measured in all 16 treatment sessions (eight of each type), which were administered over eight weeks.

Inclusion Criteria: Normal performance on a pure-tone hearing screening at 20 dB HL, a screening examination of oral-motor structure and function, and a test of receptive language. Exclusion Criteria: History of major behavioral, neurological, or hearing impairment, per parent and/or SLP report.