Dynamic Temporal and Tactile Cueing: A Treatment Strategy for Childhood Apraxia of Speech

A Goal-Writing Framework for Motor-Based Intervention for Childhood Apraxia of Speech

PURPOSE

There are multiple frameworks for goal writing that are applicable to the practice of speech-language pathology. Motor-based speech disorders are a subset of speech sound disorders that are thought to require specific elements of intervention that are typically not addressed in the traditional frameworks used in the clinical setting. The purpose of this tutorial is to review general approaches of goal writing and suggest additional elements that may be used to improve the efficiency and effectiveness of treatment for childhood motor speech disorders, specifically childhood apraxia of speech (CAS).

METHOD

Existing models of goal writing were reviewed to ascertain elements common to most of these models. A basic framework was chosen and modified to include behaviors, conditions, and approaches to goal measurement tailored to the clinical needs of children with CAS. A resource for clinical decision making for children with CAS was developed to inform goal writing at the onset of treatment and adaptations that occur over the course of treatment. Case studies are presented to demonstrate how the presented framework can be applied to writing goals for motor-based treatment for two different children with CAS.

DISCUSSION

Children with CAS require a specialized approach to intervention, which requires goals to reflect the unique clinical needs of this population. This tutorial offers resources that use the best available research evidence and current understanding of effective treatment practices for CAS to guide clinical decision making for motor-based intervention and goal writing. This tutorial is intended to guide treatment planning across varied settings to facilitate progress and optimize treatment outcomes for children with CAS.

Treatment for Childhood Apraxia of Speech: Past, Present, and Future

PURPOSE

The purposes of this review article were to provide an introduction to and "bird's-eye" overview of the current evidence base for treatment of childhood apraxia of speech (CAS), identify some gaps and trends in this rapidly growing literature, and formulate some future research directions, in order to advance the evidence base and clinical practice for children with CAS.

METHOD

Following a brief introduction outlining important concepts, a narrative review of the CAS treatment literature is provided, and trends and future directions are identified based on this review. The review is organized around four fundamental treatment research questions: (a) "Does Treatment X work?", (b) "Does Treatment X work better than Treatment Y?", (c) "For whom does Treatment X work?", and (d) "What does 'work' mean, anyway?"

RESULTS

A wide range of CAS treatments with varying degrees of evidence for efficacy exists. Research is beginning to emerge that compares different treatments and seeks to determine optimal treatment parameters. Few studies to date have explored child-level predictors of treatment response, and the evidence base currently is limited in scope with respect to populations and outcomes studied.

CONCLUSIONS

A growing evidence base supports the efficacy of a number of treatments for CAS. However, many important gaps in the literature were identified that warrant redoubled and sustained research attention. Research is beginning to emerge that addresses treatment optimization, comparison, candidacy, and outcomes. Suggestions for future research are offered, and the concept of a hypothesized pathway was applied to CAS to illustrate how components of an intervention can effect change in a clinical goal and can help guide development and refinement of treatments for children with CAS.

Dynamic Temporal and Tactile Cueing in Young Children With Childhood Apraxia of Speech: A Multiple Single-Case Design

PURPOSE

Childhood apraxia of speech (CAS) is a multivariate motor speech disorder that requires a motor-based intervention approach. There is limited treatment research on young children with CAS, reflecting a critical gap in the literature given that features of CAS are often in full expression early in development. Dynamic Temporal and Tactile Cueing (DTTC) is a treatment approach designed for children with severe CAS, yet the use of DTTC with children younger than 3 years of age has not been examined.

METHOD

A multiple single-case design was employed to examine the use of DTTC in seven children with CAS (aged 2.5-5 years) over the course of 6 weeks of intervention. Changes in word accuracy were measured in treated words from baseline to posttreatment and from baseline to maintenance (6 weeks posttreatment). Generalization of word accuracy changes to matched untreated words was also examined. A linear mixed-effects model was used to estimate the change in word accuracy for treated and untreated words across all children from baseline to posttreatment and to maintenance. A quasi-Poisson regression model was used to estimate mean change and calculate effect sizes for treated and untreated words.

RESULTS

Group-level analyses revealed significant changes in word accuracy for treated and untreated words at posttreatment and maintenance. At the child level, six of seven children displayed medium-to-large effect sizes where word accuracy increased in an average of 3.4/5 words across all children. Each child displayed some degree of generalization to untreated targets, specifically for words with the same syllable shape as the treated words.

CONCLUSIONS

These results demonstrate that DTTC can yield positive change in some young children with CAS. Key differences in each child's performance are highlighted.

A single case experimental design study using an operationalised version of the Kaufman Speech to Language Protocol for children with childhood apraxia of speech

PURPOSE

A Phase I study was conducted to examine the treatment effectiveness of the Kaufman Speech to Language Protocol using a research-operationalised protocol. It was hypothesised that articulatory accuracy would improve as a result of the treatment and that these improvements would be maintained after treatment was discontinued.

METHOD

A single case experimental design was used to evaluate the effectiveness of the Kaufman Speech to Language Protocol. Four children with a confirmed childhood apraxia of speech diagnosis were included in this study. Each child received 12 individual 1 hr treatment sessions that each consisted of an approximation setting phase and a practice phase. Probe data was collected during treatment and at post-treatment time points to measure treatment effectiveness and to measure changes in the untreated words. Untreated (control) sounds were included to test whether recorded improvements in articulatory accuracy could be attributed to the Kaufman Speech to Language Protocol.

RESULT

Two of the four children demonstrated a response to the intervention and maintenance of these changes, while the two remaining children demonstrated some generalisation in the absence of improved target (treatment) words. No specific child factors were clearly associated with positive treatment outcomes.

CONCLUSION

This study replicated the findings of an earlier pilot study and found that the operationalised protocol for the Kaufman Speech to Language Protocol is effective in improving articulatory accuracy for some children with childhood apraxia of speech. Additional replication with a further refined treatment protocol and a larger sample size is needed to support a recommendation of clinical use of the Kaufman Speech to Language Protocol.

Manual Rhythmic Sequencing Skills in Children With Childhood Apraxia of Speech

PURPOSE

Rhythm is one procedural mechanism that underlies language and motor skill acquisition and has been implicated in children with childhood apraxia of speech (CAS). The purpose of this study is to investigate manual rhythmic sequencing skills in children with a history of or current CAS (hx/CAS) compared to children with typical development (TD).

METHOD

Thirty-eight children (18 with hx/CAS, 20 with TD), ages 5;0-12;8 (years;months), from across the United States participated in an online study. Participants imitated two rhythms in two different conditions, clapping and tapping. We assessed overall accuracy, mean number of beats, pause marking, and rhythmic sequence variability using the Mann-Whitney U test. Effect sizes were calculated to examine the influence of coordinative complexity on performance.

RESULTS

Compared to children with TD, children with hx/CAS marked fewer trials with a pause in both conditions of the easier rhythm and showed lower overall accuracy and more variable rhythmic sequences in both rhythms and conditions. The mean number of beats produced by children with hx/CAS and children with TD did not differ in three out of four rhythms/conditions. Unlike children with TD, children with hx/CAS showed little improvement from clapping to tapping across most dependent measures; reducing coordination demands did not improve performance in children with hx/CAS.

CONCLUSIONS

We found that children with hx/CAS show manual rhythmic deficits that are similar to the deficits they display in speech. These findings provide support for a domain-general cognitive mechanisms account of the rhythmic deficits observed across linguistic and nonlinguistic tasks in children with hx/CAS.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24052821.

Predictors of Functional Communication Outcomes in Children With Idiopathic Motor Speech Disorders

PURPOSE

The purpose of the study was to investigate child- and intervention-level factors that predict improvements in functional communication outcomes in children with motor-based speech sound disorders.

METHOD

Eighty-five preschool-age children with childhood apraxia of speech (n = 37) and speech motor delay (n = 48) participated. Multivariable logistic regression models estimated odds ratios and 95% confidence intervals for the association between minimal clinically important difference in the Focus on the Outcomes of Communication Under Six scores and multiple child-level (e.g., age, sex, speech intelligibility, Kaufman Speech Praxis Test diagnostic rating scale) and intervention-level predictors (dose frequency and home practice duration).

RESULTS

Overall, 65% of participants demonstrated minimal clinically important difference changes in the functional communication outcomes. Kaufman Speech Praxis Test rating scale was significantly associated with higher odds of noticeable change in functional communication outcomes in children. There is some evidence that delivering the intervention for 2 times per week for 10 weeks provides benefit.

CONCLUSION

A rating scale based on task complexity has the potential for serving as a screening tool to triage children for intervention from waitlist and/or determining service delivery for this population.

Speech and Music Therapy in the Treatment of Childhood Apraxia of Speech: An Introduction and a Case Study

PURPOSE

Speech-Music Therapy for Aphasia (SMTA), a method that combines speech therapy and music therapy, is introduced as a treatment method for childhood apraxia of speech (CAS). SMTA will be evaluated in a proof-of-principle study. The first case study is presented herein.

METHOD

SMTA was evaluated in a study with a single-subject experimental design comparing 10 weeks of treatment with 2 months of no treatment. The research protocol included a pretest, baseline phase, treatment phase, posttest, no-treatment phase, and follow-up test. The participant was a boy with CAS aged 5;8 (years;months). Outcome measures were selected to reflect both intelligibility in daily communication as well as features of CAS and speech motor planning and programming.

RESULTS

Results on the Intelligibility in Context Scale-Dutch (ICS-Dutch) and in the analysis of a spontaneous speech sample suggest generalization of treatment effects. Improvements were found in measures that reflect complex speech motor skills, that is, the production of consonant clusters and consistency.

CONCLUSIONS

This case study showed that speech production of the participant improved after treatment with SMTA. Although intelligibility as measured with the ICS-Dutch improved over the study period, objectifying changes at the level of intelligibility in daily communication proved to be difficult. Additional measures may be necessary to gain more insight into treatment effects at this level. Overall, the results of this first case study provide sufficient support and important leads for further evaluation of SMTA in the treatment of CAS in a proof-of-principle study.

A Randomized Controlled Trial of Treatment Distribution and Biofeedback Effects on Speech Production in School-Age Children With Apraxia of Speech

PURPOSE

This study examines how ultrasound biofeedback and intensive treatment distribution affect speech sound generalization during an evidence-based treatment, Speech Motor Chaining, for children with persisting speech errors associated with childhood apraxia of speech (CAS).

METHOD

In a 2 × 2 factorial randomized controlled trial, children ages 9-17 years meeting CAS criteria were randomized to receive (a) a distributed treatment (20 sessions twice weekly over 10 weeks) or intensive treatment (20 hr in 5 weeks, with 10 hr in Week 1) and (b) treatment with or without biofeedback. Due to the COVID pandemic, some participants were randomized to distributed/intensive telepractice treatment only. The primary outcome was percent target sounds correct on untreated phrases (i.e., generalization) at the 10-week time point. More than 50,000 narrow phonetic transcriptions were analyzed.

RESULTS

Forty-eight participants completed treatment. Intensive treatment significantly increased generalization at all time points. The effect of biofeedback was significant at 5 weeks from the start of treatment but not significant at the primary 10-week time point. However, when comparing each group immediately after their 20 hr of treatment finished, generalization was significantly greater in intensive over distributed treatment and greater in ultrasound over no-ultrasound treatment (with a significant interaction favoring intensive treatment with ultrasound). Only the advantage of intensive treatment remained significant 5 weeks after groups finished treatment. There was no significant difference between face-to-face and telepractice modalities.

CONCLUSIONS

When the number of treatment hours is fixed, an intensive schedule of Speech Motor Chaining facilitated greater improvement than a distributed schedule. Ultrasound biofeedback initially accelerated learning, but the benefits may dissipate as treatment continues or after it ends.

The Multilevel Word Accuracy Composite Scale: A Novel Measure of Speech Production in Childhood Apraxia of Speech

PURPOSE

The Multilevel word Accuracy Composite Scale (MACS) is a novel whole-word measure of speech production accuracy designed to evaluate behaviors commonly targeted in motor-based intervention for childhood apraxia of speech (CAS). The MACS yields a composite score generated through ratings of segmental accuracy, word structure maintenance, prosody, and movement transition. This study examined the validity of the MACS through comparison to established measures of speech accuracy. Reliability was also examined within and between practicing speech-language pathologists (SLPs).

METHOD

The MACS was used to rate 117 tokens produced by children with severe CAS. Ratings were performed in the laboratory setting by two expert raters and by practicing SLPs (N = 19). Concurrent validity was estimated through comparison of expert MACS ratings (i.e., MACS score and each component rating) to measures of speech accuracy (percent phoneme correct and the 3-point scale) using correlational analyses. Reliability was examined between expert raters and across SLP raters using the intraclass correlation coefficient to examine interrater reliability of expert ratings, in addition to inter- and intrarater reliability of SLP ratings.

RESULTS

Correlation analyses between MACS ratings (i.e., MACS score and component ratings) and existing measures of speech accuracy revealed small to large positive correlations between measures. Reliability analyses revealed moderate to excellent reliability for MACS ratings performed by expert raters and between (interrater) and within (intrarater) SLP raters.

CONCLUSIONS

Analyses of concurrent validity indicate that the MACS aligns with established measures, yet contributes novel elements for rating speech accuracy. Results further support the MACS as a reliable measure for rating speech accuracy in children with severe speech impairment for ratings performed by expert raters and practicing clinicians.

Music and musical elements in the treatment of childhood speech sound disorders: A systematic review of the literature

PURPOSE

Music-based interventions are used in the treatment of childhood speech sound disorders (SSDs). Hypotheses on working mechanisms are being developed, focussing on shared neural processes. However, evidence of the effect of treatment with musical elements in SSDs in children is lacking. This study reviews the literature regarding the use of music-based interventions in the treatment of childhood SSDs.

METHOD

A systematic search in six databases was conducted, yielding 199 articles, eight of which met the inclusion criteria. Included articles were reviewed on study characteristics, patient characteristics, interventions, outcomes and methodological quality.

RESULT

This review included four case studies, three single-subject design studies and one cohort study. Seven studies reported positive outcomes on speech production, but outcome measures in the four studies with experimental design were not all aimed at the level of speech (motor) processes. Methodological quality was sufficient in one study.

CONCLUSION

Seven out of eight studies in this review report positive outcomes of music-based interventions in the treatment of SSDs. However, these outcomes are not sufficiently supported by evidence due to insufficient methodological quality. Suggestions for improving methodological quality in future research are presented.

Naive Listener Ratings of Speech Intelligibility Over the Course of Motor-Based Intervention in Children With Childhood Apraxia of Speech

PURPOSE

The aim of this study was to describe changes in speech intelligibility and interrater and intrarater reliability of naive listeners' ratings of words produced by young children diagnosed with childhood apraxia of speech (CAS) over a period of motor-based intervention (dynamic temporal and tactile cueing [DTTC]).

METHOD

A total of 120 naive listeners (i.e., listeners without experience listening to children with speech and/or language impairments; age range: 18-45 years) orthographically transcribed single-word productions by five children (age range: 2;6-3;11 [years;months]) across three time points over an intervention period (baseline, post-treatment, maintenance). Changes in intelligibility and interrater and intrarater reliability were examined within and across time points.

RESULTS

Speech intelligibility significantly increased in children with CAS over the course of treatment, and these gains were also maintained at 6 weeks posttreatment. There was poor-to-fair consistency between listeners (interrater reliability) and excellent consistency within listeners (intrarater reliability) in ratings of speech intelligibility within and across time points.

CONCLUSIONS

Motor-based intervention increases speech intelligibility following a period of DTTC treatment. Variability among naive listeners of speech intelligibility was also present, with intrarater reliability (within listeners) yielding greater consistency than interrater reliability (between listeners). The implications for including naive listeners as raters of speech intelligibility for research and clinical purposes are discussed.

The Effectiveness of Rapid Syllable Transition Treatment in Improving Communication in Children with Cerebral Palsy: A Randomized Controlled Trial

Cerebral palsy (CP) is a movement disorder and majority of children with CP have communication impairments which impact participation with this population. Rapid Syllable Transition Treatment (ReST) is a motor speech intervention primarily for children with Childhood Apraxia of Speech (CAS). A recent pilot study in which ReST was trialed with children with CP showed improved speech performance. Therefore, a single blind randomized controlled trial to compare ReST to usual care with 14 children with moderate-to-severe CP and dysarthria was conducted. ReST was provided on telehealth. ANCOVA with 95% confidence intervals indicated significant group differences in favor of ReST in speech accuracy (F = 5.1, p = .001), intelligibility (F = 2.8, p = .02) and communicative participation on both the FOCUS (F = 2, p = .02) and Intelligibility in Context Scale (F = 2.4, p = .04). ReST was found to be more effective than usual care.

Dynamic Temporal and Tactile Cueing: Quantifying Speech Motor Changes and Individual Factors That Contribute to Treatment Gains in Childhood Apraxia of Speech

PURPOSE

Speech motor skill is refined over the course of practice, which is commonly reflected by increased accuracy and consistency. This research examined the relationship between auditory-perceptual ratings of word accuracy and measures of speech motor timing and variability at pre- and posttreatment in children with childhood apraxia of speech (CAS). Furthermore, the degree to which individual patterns of baseline probe word accuracy, receptive language, and cognition predicted response to treatment was explored.

METHOD

Probe data were collected from seven children with CAS (aged 2;5-5;0 [years;months]) who received 6 weeks of Dynamic Temporal and Tactile Cueing (DTTC) treatment. Using a multidimensional approach to measuring speech performance, auditory-perceptual (whole-word accuracy), acoustic (whole-word duration), and kinematic (jaw movement variability) analyses were conducted on probe words produced pre- and posttreatment. Standardized tests of receptive language and cognition were administered pretreatment.

RESULTS

There was a negative relationship between auditory-perceptual measures of word accuracy and movement variability. Higher word accuracy was associated with lower jaw movement variability following intervention. There was a strong relationship between word accuracy and word duration at baseline, which became less robust posttreatment. Furthermore, baseline word accuracy was the only child-specific factor to predict response to DTTC treatment.

CONCLUSIONS

Following a period of motor-based intervention, children with CAS appeared to refine speech motor control in conjunction with improvements in word accuracy. Those who demonstrated the poorest performance at treatment onset displayed the greatest degree of gains. Taken together, these results reflect a system-wide change following motor-based intervention.

Lexical tone perception and production in Cantonese-speaking children with childhood apraxia of speech: a pilot study

Childhood apraxia of speech (CAS) is a paediatric motor speech disorder. We investigated the lexical tone perception and production abilities of children with CAS and the relationships between the two. Three children with CAS, aged between 3;7 and 5;8, were given the Cantonese Tone Identification Test (CANTIT) and the Hong Kong Cantonese Articulation Test (HKCAT) for assessment of tone perception and production, respectively. Accuracy and error patterns were investigated based on their performance on the two tests. Correlation analysis was performed on children's perception and production scores. Two children scored at the lowest rank on the CANTIT, while one child obtained a Z score of 0. All children scored three standard deviations below the mean on the HKCAT. No statistical differences were found among the six tones with respect to perception accuracy, H(5) = 3.731, p = 0.589. Error analysis showed that children with CAS demonstrated more confusion on perceiving tones compared with TD peers. There were no main effects for task (F(1,2) = 0.040, p = 0.859) or tone (F(5,10 = 0.997, p = 0.467); nor were there task or tone interaction effects on perception versus production accuracy (F(5,10) = 1.772, p = 0.206). Tone perception and production accuracy were not significantly correlated (r² = 0.181, p = 0.078). Tone perception deficits were evident in two out of three children with CAS, while all children had lexical tone production difficulties. In this small sample, tone production was more universally affected than tone perception.

Dose frequency randomized controlled trial for Dynamic Temporal and Tactile Cueing (DTTC) treatment for childhood apraxia of speech: protocol paper

BACKGROUND

Childhood apraxia of speech (CAS) is a pediatric motor-based speech sound disorder that requires a specialized approach to intervention. The extant literature on the treatment of CAS commonly recommends intensive treatment using a motor-based approach, with some of the best evidence supporting the use of Dynamic Temporal and Tactile Cueing (DTTC). To date, a rigorous and systematic comparison of high and low dose frequency (i.e., frequency of therapy sessions) has not been undertaken for DTTC, resulting in a lack of evidence to guide decisions about the optimal treatment schedule for this intervention. The current study aims to fill this gap in knowledge by comparing treatment outcomes when dose frequency is varied.

METHODS

A randomized controlled trial will be conducted to examine the efficacy of low versus high dose frequency on DTTC treatment outcomes in children with CAS. A target of 60 children, 2;6-7;11 years of age, will be recruited to participate in this study. Treatment will be provided in the community setting by speech-language pathologists who have completed specialized training administering DTTC in a research reliable manner. True randomization with concealed allocation will be used to assign children to either the low or high dose frequency group. Treatment will be administered in 1-h sessions either 4 times per week over a 6-week period (high dose) or 2 times per week over a 12-week period (low dose). To measure treatment gains, probe data will be collected before treatment, during treatment, and 1 day, 1 week, 4 weeks, and 12 weeks post-treatment. Probe data will consist of customized treated words and a standard set of untreated words to assess generalization of treatment gains. The primary outcome variable will be whole word accuracy, encompassing segmental, phonotactic, and suprasegmental accuracy.

DISCUSSION

This will be the first randomized controlled trial to evaluate dose frequency for DTTC treatment in children with CAS.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT05675306, January 6, 2023.

A Pilot Randomized Control Trial of Motor-Based Treatments for Childhood Apraxia of Speech: Rapid Syllable Transition Treatment and Ultrasound Biofeedback

PURPOSE

Both Rapid Syllable Transition Treatment (ReST) and ultrasound biofeedback are effective approaches to treating childhood apraxia of speech (CAS). The purpose of the study was to compare outcomes from these two motor-based treatment approaches for school-age children with CAS.

METHOD

In a single site, single blind randomized control trial, 14 children with CAS ages 6-13 years were randomly assigned to 12 sessions over 6 weeks of either of ultrasound biofeedback treatment (with a speech motor chaining practice structure) or ReST. Treatment was delivered at The University of Sydney by students trained and supervised by certified speech-language pathologists. Transcriptions from blinded assessors were used to compare the two groups on speech sound accuracy (percent phonemes correct) and prosodic severity (lexical stress errors and syllable segregation) in untreated words and sentences at three time points: pretreatment, immediately posttreatment, and 1-month posttreatment (i.e., retention).

RESULTS

Both groups showed significant improvement on treated items indicating a treatment effect. At no time was there a difference between groups. Both groups showed a significant improvement in speech sound accuracy on untreated words and sentences from pre to post and neither group showed an improvement in prosody pre-post. Changes to speech sound accuracy were retained by both groups at 1-month follow-up. Significant improvement in prosodic accuracy was reported at the 1-month follow-up.

CONCLUSIONS

ReST and ultrasound biofeedback were equally effective. Either ReST or ultrasound biofeedback may be viable treatment options for school-age children with CAS.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.22114661.

Comorbidity and Severity in Childhood Apraxia of Speech: A Retrospective Chart Review

PURPOSE

The purpose of this study was to investigate comorbidity prevalence and patterns in childhood apraxia of speech (CAS) and their relationship to severity.

METHOD

In this retroactive cross-sectional study, medical records for 375 children with CAS (M age = 4;9 [years;months], SD = 2;9) were examined for comorbid conditions. The total number of comorbid conditions and the number of communication-related comorbidities were regressed on CAS severity as rated by speech-language pathologists during diagnosis. The relationship between CAS severity and the presence of four common comorbid conditions was also examined using ordinal or multinomial regressions.

RESULTS

Overall, 83 children were classified with mild CAS; 35, with moderate CAS; and 257, with severe CAS. Only one child had no comorbidities. The average number of comorbid conditions was 8.4 (SD = 3.4), and the average number of communication-related comorbidities was 5.6 (SD = 2.2). Over 95% of children had comorbid expressive language impairment. Children with comorbid intellectual disability (78.1%), receptive language impairment (72.5%), and nonspeech apraxia (37.3%; including limb, nonspeech oromotor, and oculomotor apraxia) were significantly more likely to have severe CAS than children without these comorbidities. However, children with comorbid autism spectrum disorder (33.6%) were no more likely to have severe CAS than children without autism.

CONCLUSIONS

Comorbidity appears to be the rule, rather than the exception, for children with CAS. Comorbid intellectual disability, receptive language impairment, and nonspeech apraxia confer additional risk for more severe forms of CAS. Findings are limited by being from a convenience sample of participants but inform future models of comorbidity.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.22096622.

Changes in variability during intervention for childhood apraxia of speech: implications for therapy

Typically developing children are variable in their speech production with decreasing variability indicating mastery of speech. Excessive variability which does not change over time may be an indication of unstable motor plans as often seen in children with childhood apraxia of speech (CAS). Dynamic Systems Theory (DST) provides a framework for understanding the role of variability in speech development and disorder. There are few studies that explore the impact of therapy on speech variability. This work explores the impact of therapy on perceptual speech production variability. It is a post-hoc analysis of data collected in two intervention studies of a motor-based treatment approach with children with CAS and explores DST variability effects in speech skill acquisition based on the case data from those studies. There were six participants in total across the two studies. Findings were mixed showing some non-linear changes in variability with larger changes in variability observed in participants who engaged in more extensive therapy. However, the pattern of variability change was not consistent across the participants. These findings suggest that targeting variability in therapy may be an effective way to improve the speech of children with CAS. A model for utilising variability in therapy is presented.

Speech Error Variability and Phonological Awareness in Preschoolers

PURPOSE

The purpose of this article was to investigate the relationship between speech error variability and phonological awareness.

METHOD

This article begins with a narrative review of the theoretical interpretation of speech error variability. The post hoc exploratory analysis of the relationship between speech error variability and phonological awareness included 40 children: 20 with typical speech and language and 20 with speech sound disorder and typical language. Groups were matched on gender, age, maternal education, receptive and expressive vocabulary, nonverbal intelligence, and expressive morphosyntax. Multiple regression was used to identify the best fit model for the relationship between vocabulary, speech errors, and phonological awareness.

RESULTS

Segmental variability was associated with poor phonological awareness in preschool-aged children.

CONCLUSION

Children with high levels of segmental variability have poor phonological awareness, likely due to unstable phonological representations.

Speech Perception Variability in Childhood Apraxia of Speech: Implications for Assessment and Intervention

PURPOSE

Beyond hallmark production deficits characterizing childhood apraxia of speech (CAS), largely attributed to disruption(s) in speech motor planning, children with CAS often present with co-occurring speech perception and language difficulties. Thus, careful consideration of the potential for speech perception difficulties to have cascading downstream effects on intervention responsiveness and real-life functioning for some children with CAS is highly important. The purpose of this tutorial was to consider the impact of speech perception abilities in children with CAS, which carries implications for caring for the needs of the whole child.

METHOD

This tutorial summarizes the current literature on speech perception and how it relates to speech production, language, and reading abilities for children with CAS. We include case illustrations that are adapted from real clinical scenarios illustrating how speech perception difficulties may impact some children with CAS and provide recommendations for incorporating speech perception into assessment and intervention practices.

RESULTS

Although speech perception difficulties do not seem to be a core deficit of CAS, they are strongly linked to language difficulties, which are highly prevalent among children with CAS. Speech perception and language difficulties are also associated with reading difficulties and risk for lower academic achievement.

CONCLUSIONS

Children with CAS who have co-occurring language difficulties likely also demonstrate speech perception deficits, which puts them at heightened risk for reading difficulties and struggles with academic achievement. Comprehensive assessment of children with CAS should address speech perception and production, language, and reading abilities, which carries important implications for multifaceted approaches to intervention.

Graduate Student Clinicians' Perceptions of Child Speech Sound Errors

Purpose

Speech-language pathologists (SLPs) rely on auditory perception to form judgments on child speech. This can be challenging for graduate student clinicians with limited clinical experience as they often need to judge children's speech errors using their auditory perception. This study examined how consistently graduate student clinicians used a 3-point perceptual rating scale to judge child speech.

Method

Twenty-four graduate student clinicians rated single words produced by children with typically developing speech and language skills and children with speech sound disorders. All participants rated the productions using a 3-point scale, where "2" was an accurate production, "1" was a close approximation, and "0" was an inaccurate production. Ratings were solely based on the auditory signal. These ratings were compared to a consensus rating formed by two experienced SLPs.

Results

Graduate student clinicians reached substantial agreement with the expert SLP rating. They reached the highest percentage agreement when rating accurate productions, and the lowest agreement when rating inaccurate productions.

Conclusions

Graduate student clinicians reached substantial agreement with expert SLP rating in judging child speech using a 3-point scale when provided with detailed descriptions of each rating category. These results are consistent with previous findings on the role that clinical experience plays in speech error perception tasks and highlight the need for additional listening training in speech-language pathology graduate programs.

Predictors of Speech Severity and Inconsistency Over Time in Children With Token-to-Token Inconsistency

PURPOSE

The aim of this study was to describe and explain changes in severity of speech sound disorder (SSD) and token-to-token inconsistency in children with high levels of inconsistency.

METHOD

Thirty-nine children (aged 4;6-7;11 [years;months]) with SSDs and high levels of token-to-token inconsistency were assessed every 6 months for 2 years (i.e., five assessment points). Growth modeling was used to assess relations among therapy support, receptive vocabulary, severity, and inconsistency over time.

RESULTS

Children with the most severe SSDs and highest levels of token-to-token inconsistency showed the smallest improvements in speech accuracy over time. Therapy support did not predict changes in speech accuracy or token-to-token inconsistency over time. Receptive vocabulary (measured at the outset of the study) was also a significant predictor of speech accuracy and inconsistency.

CONCLUSIONS

These findings suggest that an immediate start to intervention (rather than a wait-and-see approach) is recommended for children with inconsistent speech error patterns. The results also highlight the value of developing vocabulary knowledge in addition to improving speech accuracy for some children with inconsistent speech production.

Speech Sound Disorder Treatment Approaches Used by School-Based Clinicians: An Application of the Experience Sampling Method

PURPOSE

Children with speech sound disorders (SSDs) comprise a large portion of caseloads for school-based speech-language pathologists (SLPs). Despite the existence of several evidence-based SSD intervention approaches, the translation from research to practice is often limited by ecological validity because of various factors unique to school settings (e.g., scheduling constraints, caseload size, child availability). The purpose of this study was to use the experience sampling method (ESM) to examine the current practices of school-based SLPs when treating children with SSDs on their caseloads.

METHOD

SLPs (N = 106) from 42 different states working full-time in school-based K-12 settings participated in this study. At the beginning of the study, each SLP completed a one-time demographic survey about treatment practices for children with SSDs. The SLPs then participated in a series of brief surveys every day for one workweek using a specialized ESM phone application that randomly alerted participants to report on their treatment practices for children with SSDs.

RESULTS

Findings revealed that although most SLPs reported using a variety of SSD intervention approaches in a one-time survey, the majority of SLPs reported using one of three approaches in situ: the traditional articulation therapy approach, cycles, and minimal pairs. We also report a significant negative relationship between the years of experience of an SLP and the number of different approaches used.

CONCLUSIONS

This study is the first to use the ESM to determine which approaches school-based SLPs use to treat children with SSDs. Findings demonstrate that SLPs have knowledge of many different SSD approaches but tend to utilize only a few in school-based settings.

Predicting Treatment Outcomes in Rapid Syllable Transition Treatment: An Individual Participant Data Meta-Analysis

PURPOSE

The purpose of this study is to identify predictors of treatment outcomes in Rapid Syllable Transition Treatment (ReST) for childhood apraxia of speech through an individual participant data meta-analysis.

METHOD

A systematic literature search identified nine ReST studies for inclusion. Individual participant data were obtained, and studies were coded for methodological design, baseline participant characteristics, service delivery factors, and treatment outcomes. Bivariate analyses were conducted to identify potential predictor variables. Multiple linear regressions were then performed to identify predictors of treatment outcomes.

RESULTS

Data for 36 participants from seven studies were included in the statistical analyses. In multivariate modeling, better performance on treated pseudowords posttreatment was predicted by higher baseline expressive language and Goldman-Fristoe Test of Articulation scores, lower speech inconsistency and percentage of vowels correct, and higher pretreatment accuracy on pseudoword targets. Better performance on untreated real words posttreatment was predicted by higher pretreatment accuracy on real words. Gains in performance and retention of gains were not significantly predicted by any individual variable or combination of variables.

CONCLUSIONS

Baseline speech and expressive language skills and accuracy on pseudowords and real words were significant predictors of absolute posttreatment performance. Regardless of baseline characteristics, all children were statistically as likely to achieve gains during ReST and retain these gains for up to 4 weeks posttreatment. Large-scale prospective research is required to further examine the effects of dose frequency and co-occurring language impairments on treatment outcomes and the complex co-effects of percentage of vowels correct with other potential predictors.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19611714.

A Tool for Differential Diagnosis of Childhood Apraxia of Speech and Dysarthria in Children: A Tutorial

PURPOSE

While there has been mounting research centered on the diagnosis of childhood apraxia of speech (CAS), little has focused on differentiating CAS from pediatric dysarthria. Because CAS and dysarthria share overlapping speech symptoms and some children have both motor speech disorders, differential diagnosis can be challenging. There is a need for clinical tools that facilitate assessment of both CAS and dysarthria symptoms in children. The goals of this tutorial are to (a) determine confidence levels of clinicians in differentially diagnosing dysarthria and CAS and (b) provide a systematic procedure for differentiating CAS and pediatric dysarthria in children.

METHOD

Evidence related to differential diagnosis of CAS and dysarthria is reviewed. Next, a web-based survey of 359 pediatric speech-language pathologists is used to determine clinical confidence levels in diagnosing CAS and dysarthria. Finally, a checklist of pediatric auditory-perceptual motor speech features is presented along with a procedure to identify CAS and dysarthria in children with suspected motor speech impairments. Case studies illustrate application of this protocol, and treatment implications for complex cases are discussed.

RESULTS

The majority (60%) of clinician respondents reported low or no confidence in diagnosing dysarthria in children, and 40% reported they tend not to make this diagnosis as a result. Going forward, clinicians can use the feature checklist and protocol in this tutorial to support the differential diagnosis of CAS and dysarthria in clinical practice.

CONCLUSIONS

Incorporating this diagnostic protocol into clinical practice should help increase confidence and accuracy in diagnosing motor speech disorders in children. Future research should test the sensitivity and specificity of this protocol in a large sample of children with varying speech sound disorders. Graduate programs and continuing education trainings should provide opportunities to practice rating speech features for children with dysarthria and CAS.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19709146.

Diagnosis and Treatment of Childhood Apraxia of Speech Among Children With Autism: Narrative Review and Clinical Recommendations

PURPOSE

Treatment for children with autism spectrum disorder (ASD) and low verbal ability is a largely neglected area of study. Existing research focuses on language abilities; however, a subset of children with ASD also has speech sound disorders (SSDs). The purpose of this tutorial is to provide clinicians with evidence-based recommendations to guide speech assessment and treatment among children with ASD, low verbal ability, and suspected childhood apraxia of speech (CAS).

METHOD

Multifaceted search procedures were used to identify studies that have assessed or treated speech sound production among children with ASD. A narrative review and synthesis of the literature is followed by practical clinical recommendations based on best available evidence.

CONCLUSIONS

It is critically important to consider all possible hindrances to the development of functional communication ability for children with ASD. Speech sound production has been identified as a key predictor of expressive language outcomes, yet there are very few studies that address assessment and treatment of SSDs among children with ASD. Less is known about the presentation of CAS among children with ASD and low verbal ability. More research is needed to determine whether existing speech assessment and treatment methods are appropriate for children with ASD, if modifications are needed, or if new methods should be designed.

A survey of the clinical management of childhood apraxia of speech in the United States and Canada

PURPOSE

Limited information is available about the current practices of generalist speech-language pathologists (SLPs) in relation to their management of childhood apraxia of speech (CAS). This study was designed to investigate four primary questions separately for the US and Canada; 1. What treatment approaches are used by SLP clinicians to treat CAS? 2. What treatment format and intensity are used to deliver CAS treatment? 3. What are the attitudes and perspectives of SLPs to evidence-based practice (EBP) as it pertains to CAS treatment? and 4. What are the perceived barriers to the implementation of EBP in CAS treatment?

METHOD

An online questionnaire was used to investigate the four primary research questions. The questionnaire was distributed online through social media, some state-based associations and through forums affiliated with national speech-language-hearing associations.

RESULTS

Most survey respondents reported frequently using an eclectic approach to treat CAS (US 85%; Canada 89%). Although no intervention emerged as the most preferred primary treatment for CAS, US-based clinicians more commonly reported using the Kaufman Speech to Language Protocol (K-SLP) (33%) and Dynamic, Temporal and Tactile Cueing (DTTC) (28%); while clinicians in Canada used PROMPT ® (31%). SLPs demonstrated a positive attitude towards EBP however, they identified a range of perceived barriers that impacted their implementation of EBP.

CONCLUSION

SLPs in the US and Canada frequently used an eclectic approach to treat CAS which is consistent with previous findings both in the CAS literature and the wider speech disorders literature. The more commonly used primary interventions were the K-SLP and DTTC (US); and PROMPT ® (Canada), with one of the strongest factors that influenced clinicians' choice of intervention being familiarity with the treatment approach. Face to face therapy was preferred by clinicians across both countries, with clinicians in the US providing therapy between 2-5 times per week, while those in Canada delivered therapy up to once per week. Clinicians identified a number of barriers to implementing evidence-based practice, among which, being time poor was most commonly selected across clinicians in both the US and Canada.

Speech-Language Pathologists' Ratings of Speech Accuracy in Children With Speech Sound Disorders

PURPOSE

Forming accurate and consistent speech judgments can be challenging when working with children with speech sound disorders who produce a large number and varied types of error patterns. Rating scales offer a systematic approach to assessing the whole word rather than individual sounds. Thus, these scales can be an efficient way for speech-language pathologists (SLPs) to monitor treatment progress. This study evaluated the interrater reliability of an existing 3-point rating scale using a large group of SLPs as raters.

METHOD

Utilizing an online platform, 30 SLPs completed a brief training and then rated single words produced by children with typical speech patterns and children with speech sound disorders. Words were closely balanced across the three rating categories of the scale. The interrater reliability of the SLPs ratings to a consensus judgment was examined.

RESULTS

The majority of SLPs (87%) reached substantial interrater reliability to a consensus judgment using the 3-point rating scale. Correct productions had the highest interrater reliability. Productions with extensive errors had higher agreement than those with minor errors. Certain error types, such as vowel distortions, were especially challenging for SLPs to judge.

CONCLUSIONS

This study demonstrated substantial interrater reliability to a consensus judgment among a large majority of 30 SLPs using a 3-point rating. The clinical implications of the findings are discussed along with proposed modifications to the training procedure to guide future research.

The Bouba-Kiki Effect in Children With Childhood Apraxia of Speech

PURPOSE

The bouba-kiki (BK) effect refers to associations between visual shapes and auditory pseudonames. Thus, when tested, people tend to associate the pseudowords bouba and kiki with round or spiky shapes, respectively. This association requires cross-modal sensory integration. The ability to integrate information from different sensory modalities is crucial for speech development. A clinical population that may be impaired in cross-modal sensory integration is children with childhood apraxia of speech (CAS). The purpose of this study was to examine the involvement of cross-modal sensory integration in children with (CAS).

METHOD

The BK effect was assessed in participants with CAS (n = 18) and two control groups: One control group was composed of children with developmental language disorder (DLD), also termed specific language impairment (n = 15), and a second group included typically developing (TD) children (n = 22). The children were presented with 14 pairs of novel visual displays and nonwords. All the children were asked to state which shape and nonword correspond to one another. In addition, background cognitive (Leiter-3) and language measures (Hebrew PLS-4) were determined for all children.

RESULTS

Children in the CAS group were less successful in associating between visual shapes and corresponding auditory pseudonames (e.g., associating the spoken word "bouba" with a round shape; the spoken word "kiki" with a spiky shape). Thus, children with CAS demonstrated a statistically significant reduced BK effect compared with participants with TD and participants with DLD. No significant difference was found between the TD group and the DLD group.

CONCLUSIONS

The reduced BK effect in children with CAS supports the notion that cross-modal sensory integration may be altered in these children. Cross-modal sensory integration is the basis for speech production. Thus, difficulties in sensory integration may contribute to speech difficulties in CAS.

Application of the Challenge Point Framework During Treatment of Speech Sound Disorders

Purpose The purpose of this article is to provide trial-by-trial practice performance data in relation to learning (outcome probe data) as collected from 18 treatment sessions provided to children with severe speech sound disorders. The data illustrate the practice-learning paradox: Specific, perfect practice performance is not required for speech production learning. Method We detailed how nine student speech-language pathologists (SSLPs) implemented and modified the motor learning practice conditions to reach a proposed challenge point during speech practice. Eleven participants diagnosed with a severe speech sound disorder received high-intensity speech therapy 3 times per week for 6 weeks. SSLPs implemented treatment procedures with the goal of achieving at least 100 practice trials while manipulating practice parameters to maintain practice at the challenge point. Specifically, child performance was monitored for accuracy in five-trial increments, and practice parameters were changed to increase functional task difficulty when the child's performance was high (four or five correct responses) or to decrease functional task difficulty when the child's performance was low (fewer than four correct responses). The practice stimulus, type and amount of feedback, structure of practice, or level of support might be changed to ensure practice at the challenge point. Results On average, the children achieved 102 practice trials per session at a level of 58% correct responses. Fast achievement of connected speech with the lowest amount of support was associated with high scores on generalization probes. Even with high levels of error during practice, the children improved percent consonants correct with maintenance of learning 3 months posttreatment. Conclusion The results of this study show that it may not be necessary to overpractice or maintain a high degree of performance accuracy during treatment sessions to achieve transfer and retention of speech production learning.

The Effect of Practice on Variability in Childhood Apraxia of Speech: A Multidimensional Analysis

Purpose Variability has been interpreted in differing ways according to context (e.g., development, speech impairment, and learning). A challenge arises when interpreting variability in the context of learning for children with speech impairment characterized by high movement variability, as in childhood apraxia of speech (CAS). The objective of this study is to investigate changes in variability in CAS with practice in comparison to patterns seen in children with non-CAS speech sound disorders (SSD) and typical development. Method Speech production variability was examined in 24 children (5-6 years of age) with CAS, non-CAS SSD, and typical development in production of nonwords of varied motoric complexity. Multidimensional analyses were performed using measures of token-to-token speech consistency (percent word consistency), acoustic variability (acoustic spatiotemporal index), and movement variability (lip aperture spatiotemporal index). Changes in variability were examined in each group of children by comparing the first half to the last half of nonword tokens in the same data collection session. The impact of token complexity on practice effects was also explored across groups of children. Results All children displayed increased speech consistency within this practice period (p = .01). Only children with CAS displayed increased movement variability following practice (p = .01). Differences in acoustic and kinematic variability were observed across complexity levels in all groups, though these did not interact with practice effects. Discussion These findings suggest that increased movement variability in children with CAS might be facilitating perceptual consistency. It is believed that this finding reflects an inefficient strategy adapted by children with CAS in the absence of motor-based cueing and feedback to guide speech performance with practice.

A Pilot Single-Case Experimental Design Study of Rapid Syllable Transition Treatment for Italian Children With Childhood Apraxia of Speech

Background The Rapid Syllable Transition (ReST) treatment is an effective intervention designed to address the planning and programming disorder found in childhood apraxia of speech. To date, no study has considered its use with children who speak languages other than English. Aim This pilot study aimed to examine the use of ReST treatment with Italian children. We hypothesized that the ReST approach would improve the overall accuracy of the targeted behaviors of lexical stress, smoothness, and phonemic accuracy, whereas phonemic and phonetic accuracy of untreated items would remain stable. Method Two monolingual Italian-speaking children with childhood apraxia of speech received therapy in 12 one-hour sessions, 2-3 times per week, using a single-case experimental design. The treatment procedures used in English were replicated in Italian with one change: In English, two stress patterns are treated. Italian commonly uses three stress patterns; therefore, the stimuli were modified accordingly. Accuracy of articulation, lexical stress, and smoothness were assessed at pretreatment and 1 day, 1 week, and 4 months posttreatment in treated and untreated pseudowords and in real words and sentences. Results Both children improved on treated pseudowords and real words with moderate effect sizes, but only one child generalized to untreated pseudowords. Maintenance of treatment results was observed in both participants. Articulation of control phonemes did not change. Conclusions ReST treatment in Italian is feasible, and a treatment effect was found, showing that its use may be valid in languages other than English. Further research is required. Supplemental Material https://doi.org/10.23641/asha.14348060.

Autism-Centered Therapy for Childhood Apraxia of Speech (ACT4CAS): A Single-Case Experimental Design Study

Purpose A subset of children with autism spectrum disorder (ASD) has speech sound disorders, including childhood apraxia of speech (CAS). To date, virtually all speech treatment studies consider ASD an exclusionary criterion, resulting in little scientific evidence for treatment of CAS for children who also have ASD. This study proposes and tests a novel approach, Autism-Centered Therapy for Childhood Apraxia of Speech (ACT4CAS), as a theoretically and clinically informed speech treatment option for this population. Method Using a multiple-baseline design within and across participants, three children with co-occurring ASD and CAS received 11-18 treatment sessions. Treatment targets were individually designed and matched with untreated control words. Probes were administered at the start of each session to assess speech production accuracy perceptually. Changes in production accuracy were examined through visual inspection and quantified with effect sizes. Results Findings were mixed, with one child showing significant gains for half of the treated targets at follow-up and two children showing no clear improvement. Conclusions Preliminary evidence suggests potentially positive treatment effects for ACT4CAS when implemented as intended, although treatment intensity and disorder severity likely influence treatment outcome. Replication and comparison of ACT4CAS to other speech treatments is needed. Supplemental Material https://doi.org/10.23641/asha.14110445.

A Framework of Motoric Complexity: An Investigation in Children With Typical and Impaired Speech Development

Introduction The current work presents a framework of motoric complexity where stimuli differ according to movement elements across a sound sequence (i.e., consonant transitions and vowel direction). This framework was then examined in children with childhood apraxia of speech (CAS), other speech sound disorders (SSDs), and typical development (TD). Method Twenty-four children (CAS, n = 8; SSD, n = 8; TD, n = 8), 5-6 years of age, participated in this study. The children produced words that varied in motoric complexity while transcription, acoustic, and kinematic data were collected. Multidimensional analyses were conducted to examine speech production accuracy, speech motor variability, and temporal control. Results Analyses revealed poorer accuracy, longer movement duration, and greater speech motor variability in children with CAS than TD (across all measures) and other SSDs (accuracy and variability). All children demonstrated greater speech motor variability and longer duration as movement demands increased within the framework of motoric complexity. Diagnostic grouping did not mediate performance on this task. Conclusions Results of this study are believed to reveal gradations of complexity with increasing movement demands, thereby supporting the proposed framework of motoric complexity. This work also supports the importance of considering motoric properties of sound sequences when evaluating speech production skills and designing experimental and treatment stimuli.

How the Study of Speech Motor Control Can Inform Assessment and Intervention in Childhood Apraxia of Speech

Purpose

The study of speech motor control has led to great advancements in the current understanding of childhood apraxia of speech (CAS). There remains a significant need to bridge the gap between theory and practice to fully understand the clinical implications of past research.

Method

This review article reviews the speech motor control research in CAS and discusses how these works have offered key information about the underlying motor deficits (Grigos et al., 2015; Terband et al., 2019), the influence of structured practice on speech performance (Case & Grigos, 2016; Grigos & Case, 2018), and the role of task complexity (Case, 2019; Case & Grigos, 2016; Grigos & Case, 2018). We highlight salient points from this existing literature and clinical implications to the assessment and treatment of CAS.

Conclusion

The study of speech motor control has shed light on a number of key factors related to CAS. Even within perceptually accurate speech, children with CAS display differences in movement patterning and timing control. Assessment must aim to more directly tax speech motor skills to obtain a thorough and accurate illustration of production deficits. Intervention is challenged with the task of not only improving production accuracy but also facilitating more efficient motor planning and programming. Motor-based intervention that applies motor learning principles and introduces variability across motor, phonetic, and prosodic contexts is believed to achieve this goal, though research is needed to better understand changes in speech motor control with treatment.

Modelling speech motor programming and apraxia of speech in the DIVA/GODIVA neurocomputational framework

BACKGROUND

The Directions Into Velocities of Articulators (DIVA) model and its partner, the Gradient Order DIVA (GODIVA) model, provide neurobiologically grounded, computational accounts of speech motor control and motor sequencing, with applications for the study and treatment of neurological motor speech disorders.

AIMS

In this review, we provide an overview of the DIVA and GODIVA models and how they explain the interface between phonological and motor planning systems to build on previous models and provide a mechanistic accounting of apraxia of speech (AOS), a disorder of speech motor programming.

MAIN CONTRIBUTION

Combined, the DIVA and GODIVA models account for both the segmental and suprasegmental features that define AOS via damage to (i) a speech sound map, hypothesized to reside in left ventral premotor cortex, (ii) a phonological content buffer hypothesized to reside in left posterior inferior frontal sulcus, and/or (iii) the axonal projections between these regions. This account is in line with a large body of behavioural work, and it unifies several prior theoretical accounts of AOS.

CONCLUSIONS

The DIVA and GODIVA models provide an integrated framework for the generation and testing of both behavioural and neuroimaging hypotheses about the underlying neural mechanisms responsible for motor programming in typical speakers and in speakers with AOS.