Neural Changes in Children With Residual Speech Sound Disorder After Ultrasound Biofeedback Speech Therapy.

PURPOSE: Children with residual speech sound disorders (RSSD) have shown differences in neural function for speech production, as compared to their typical peers; however, information about how these differences may change over time and relative to speech therapy is needed. To address this gap, we used functional magnetic resonance imaging (fMRI) to examine functional activation and connectivity on adaptations of the syllable repetition task (SRT-Early Sounds and SRT-Late Sounds) in children with RSSD before and after a speech therapy program. METHOD: Sixteen children with RSSD completed an fMRI experiment before (Time 1) and after (Time 2) a speech therapy program with ultrasound visual feedback for /ɹ/ misarticulation. Progress in therapy was measured via perceptual ratings of productions of untreated /ɹ/ word probes. To control for practice effects and developmental change in patterns of activation and connectivity, 17 children with typical speech development (TD) completed the fMRI at Time 1 and Time 2. Functional activation was analyzed using a region-of-interest approach and functional connectivity was analyzed using a seed-to-voxel approach. RESULTS: Children with RSSD showed a range of responses to therapy. After correcting for multiple comparisons, we did not observe any statistically significant cross-sectional differences or longitudinal changes in functional activation. A negative relationship between therapy effect size and functional activation in the left visual association cortex was on the SRT-Late Sounds after therapy, but it did not survive correction for multiple comparisons. Significant longitudinal changes in functional connectivity were observed for the RSSD group on SRT-Early Sounds and SRT-Late Sounds, as well as for the TD group on the SRT-Early Sounds. RSSD and TD groups showed connectivity differences near the left insula on the SRT-Late Sounds at Time 2. CONCLUSION: RSSD and treatment with ultrasound visual feedback may thus be associated with neural differences in speech motor and visual association processes recruited for speech production.

Variable Practice to Enhance Speech Learning in Ultrasound Biofeedback Treatment for Childhood Apraxia of Speech: A Single Case Experimental Study.

PURPOSE: The purpose of this study was to evaluate the role of practice variability, through prosodic variation during speech sound training, in biofeedback treatment for children with childhood apraxia of speech. It was hypothesized that variable practice would facilitate speech sound learning. METHOD: Six children ages 8-16 years with persisting speech sound errors due to childhood apraxia of speech participated in a single-subject experimental design. For each participant, 2 speech sound targets were treated with ultrasound visual feedback training: one with prosodic variation (i.e., practicing sound targets in words and phrases spoken fast, slow, loud, as a question, command, and declarative), and one without prosodic variation. Each target was treated for half of the 1-hr session for 14 treatment sessions. RESULTS: As measured by standardized effect sizes, all participants showed greater change on generalization probes for sound targets treated under the prosodic variation condition with mean effect sizes (d2) of 14.5 for targets treated with prosodic variation and 8.3 for targets treated without prosodic variation. The average increase in generalization scores was 38% in the prosodic variation condition compared to 31% without. CONCLUSIONS: Ultrasound visual feedback may facilitate speech sound learning and learning may be enhanced by treating speech sounds with explicit prosodic variation. SUPPLEMENTAL MATERIALS: https://doi.org/10.23641/asha.5150119.

Direction of attentional focus in biofeedback treatment for /r/ misarticulation.

BACKGROUND: Maintaining an external direction of focus during practice is reported to facilitate acquisition of non-speech motor skills, but it is not known whether these findings also apply to treatment for speech errors. This question has particular relevance for treatment incorporating visual biofeedback, where clinician cueing can direct the learner's attention either internally (i.e., to the movements of the articulators) or externally (i.e., to the visual biofeedback display). AIMS: This study addressed two objectives. First, it aimed to use single-subject experimental methods to collect additional evidence regarding the efficacy of visual-acoustic biofeedback treatment for children with /r/ misarticulation. Second, it compared the efficacy of this biofeedback intervention under two cueing conditions. In the external focus (EF) condition, participants' attention was directed exclusively to the external biofeedback display. In the internal focus (IF) condition, participants viewed a biofeedback display, but they also received articulatory cues encouraging an internal direction of attentional focus. METHODS & PROCEDURES: Nine school-aged children were pseudo-randomly assigned to receive either IF or EF cues during 8 weeks of visual-acoustic biofeedback intervention. Accuracy in /r/ production at the word level was probed in three to five pre-treatment baseline sessions and in three post-treatment maintenance sessions. Outcomes were assessed using visual inspection and calculation of effect sizes for individual treatment trajectories. In addition, a mixed logistic model was used to examine across-subjects effects including phase (pre/post-treatment), /r/ variant (treated/untreated), and focus cue condition (internal/external). OUTCOMES & RESULTS: Six out of nine participants showed sustained improvement on at least one treated /r/ variant; these six participants were evenly divided across EF and IF treatment groups. Regression results indicated that /r/ productions were significantly more likely to be rated accurate post- than pre-treatment. Internal versus external direction of focus cues was not a significant predictor of accuracy, nor did it interact significantly with other predictors. CONCLUSIONS: The results are consistent with previous literature reporting that visual-acoustic biofeedback can produce measurable treatment gains in children who have not responded to previous intervention. These findings are also in keeping with previous research suggesting that biofeedback may be sufficient to establish an external attentional focus, independent of verbal cues provided. The finding that explicit articulator placement cues were not necessary for progress in treatment has implications for intervention practices for speech-sound disorders in children.

Limited acquisition and generalisation of rhotics with ultrasound visual feedback in childhood apraxia.

Ultrasound visual feedback of the tongue is one treatment option for individuals with persisting speech sound errors. This study evaluated children's performance during acquisition and generalisation of American English rhotics using ultrasound feedback. Three children aged 10-13 with persisting speech sound errors associated with childhood apraxia of speech (CAS) were treated for 14 one-hour sessions. Two of the participants increased the accuracy of their rhotic production during practise trials within treatment sessions, but none demonstrated generalisation to untreated words. Lack of generalisation may be due to a failure to acquire the target with sufficient accuracy during treatment, or to co-existing linguistic weaknesses that are not addressed in a motor-based treatment. Results suggest a need to refine the intervention procedures for CAS and/or a need to identify appropriate candidates for intervention to optimise learning.

Speech motor programming in apraxia of speech: evidence from a delayed picture-word interference task.

PURPOSE: Apraxia of speech (AOS) is considered a speech motor programming impairment, but the specific nature of the impairment remains a matter of debate. This study investigated 2 hypotheses about the underlying impairment in AOS framed within the Directions Into Velocities of Articulators (DIVA; Guenther, Ghosh, & Tourville, 2006) model: The retrieval hypothesis states that access to the motor programs is impaired, and the damaged programs hypothesis states that the motor programs themselves are damaged. METHOD: The experiment used a delayed picture-word interference paradigm in which participants prepare their response and auditory distracters are presented with the go signal. The overlap between target and distracter words was manipulated (i.e., shared sounds or no shared sounds), and participants' reaction times (RTs) were measured. Participants included 5 speakers with AOS (4 with concomitant aphasia), 2 speakers with aphasia without AOS, and 9 age-matched control speakers. RESULTS: The control speakers showed no effects of distracter type or presence. The speakers with AOS had longer RTs in the distracter condition compared to the no-distracter condition. The speakers with aphasia without AOS were comparable to the control group in their overall RTs and RT pattern. CONCLUSION: Results provide preliminary support for the retrieval hypothesis, suggesting that access to motor programs may be impaired in speakers with AOS. However, the possibility that the motor programs may also be damaged cannot be ruled out.

Effects of feedback frequency and timing on acquisition, retention, and transfer of speech skills in acquired apraxia of speech.

PURPOSE: Two studies examined speech skill learning in persons with apraxia of speech (AOS). Motor-learning research shows that delaying or reducing the frequency of feedback promotes retention and transfer of skills. By contrast, immediate or frequent feedback promotes temporary performance enhancement but interferes with retention and transfer. These principles were tested in the context of a common treatment for AOS. METHOD: Two studies (N = 4, N = 2) employed single-subject treatment designs to examine acquisition and retention of speech skills in adults with AOS under different feedback conditions. RESULTS: Reduced-frequency or delayed feedback enhanced learning in 3 participants with AOS. Feedback manipulation was not an influential variable in 3 other cases in which stimulus-complexity effects may have masked treatment effects. CONCLUSIONS: These findings demonstrate that individuals with AOS can benefit from structured intervention. They provide qualified support for reduction and delay of feedback, although interaction with other factors such as stimulus complexity or task difficulty needs further exploration. This study adds to the growing body of literature investigating the use of principles of motor learning in treating AOS and provides impetus for consideration of pre-treatment variables that affect outcome in treatment studies.