Benway & Preston (2020)

January 31, 2022

ANALYSIS GUIDELINES

Comparison/Nonintervention Research 

KEY:

CAS = childhood apraxia of speech

eta =   partial eta squared 

MSWR = multisyllable word repetition 

NA = Not Applicable

nonCAS SSD = speech sound disorder without the diagnosis of childhood apraxia of speech

P = participant or patient

PCC = Percent Consonants Correct 

pmh = Patricia Hargrove, blog developer

SD = standard deviation(s)

SLP = speech-language pathologist

SS = standard score

SSD = speech sound disorders

SOURCE:  Benway, N. R., & Preston, J. L. (2020). Differences between school-age children with apraxia of speech and other speech sound disorders on multisyllable repetition. Perspectives of the ASHA Special Interest Groups, 5(4) 794-808 2020. https://doi.org/10.1044/2020_PERSP-19-00086

REVIEWER(S): pmh

DATE: January 29, 2022

ASSIGNED GRADE FOR OVERALL QUALITY:  Not Applicable

TAKE AWAY:  This investigation compared 7 to 17 year-old children with childhood apraxia of speech (CAS) with children with other speech sound disorders (SSD) on a task involving the repetition of multisyllabic words. The purpose of the investigation was to determine which of 15 features derived from the extant research could be used to distinguish the 2 groups of school-aged children. The investigators analyzed previously recorded imitations of multisyllable words of children with CAS and SSD using the 15 features. They determined that the children’s production 4 of the perceptual features differed significantly. One of these features was correct lexical stress. (The others were prevalence of voicing changes, percentage of structurally correct words, and syllable deletions.) Thus, incorrect stress may continue through childhood and has potential for distinguishing children with CAS and SSD (along with the other perceptual features.)

1.  What type of evidence was identified? 

• What was the type of design? Comparison Research and Retrospective, Nonrandomized Group Design with Controls

• What was the focus of the research? Clinically Related

• What was the level of support associated with the type of evidence?  Level = not applicable (NA). This was not an intervention study.

2.  Group membership determination: 

• If there were groups, were participants randomly assigned to groups? No 

• If there were groups and Ps were not randomly assigned to groups, were members of groups carefully matched?  No

3.  Were experimental conditions concealed?

• from participants? No 

• from administrators of experimental conditions? No 

• from analyzers/judges? Yes 

4.  Were the groups adequately described?  Variable 

 How many participants were involved in the study? 

•  total # of Ps: 61

•  # of groups: 2

•  List names of groups and the number of Ps in each group:  

     – CAS = 21

     – nonCAS SSD = 40

•  Did all groups maintain membership throughout the investigation? Yes  

CONTROLLED CHARACTERISTICS

•  age:  7 to 17 years

•  cognitive skills:  nonverbal IQ of not less than 1.33 standard deviations (SD) below the mean

:  

•  receptive language:  not less than 1.33 standard deviations (SD) below the mean

•  articulation:  below the 7th percentile on a standardized articulation test

•  Hearing:  passed a hearing screening

DESCRIBED CHARACTERISTICS

•  age:  

     – CAS = 11.92 (mean)

     – nonCAS SSD =  11.06 (mean)

•  gender: 

     – CAS = 16 (80%, male); 4 (20%, female) 

     – nonCAS SSD = 23 (56%, male); 18 (44%, female). 

•  phonological processing:  

     – CAS = 85.55 (mean)

     – nonCAS SSD = 101.44 (mean)

•  receptive vocabulary:

     – CAS = 103.15 (mean)

     – nonCAS SSD =  113.56 (mean)

• Syllable Repetition Task- Percent Consonants Correct (PCC):  

     – CAS = 85% (mean)

     – nonCAS SSD = 92% (mean)

• Syllable Repetition Task- Additions:  

     – CAS =  3.37  (mean)

     – nonCAS SSD = 0.75 (mean)

•  articulation skill:

     – CAS = standard score (SS) was 53.5 (mean)

     – nonCAS SSD =  SS  was 72.2  (mean)

•  Maximum Performance Task- Dysarthria Score:

     – CAS =  0.26 (mean)

     – nonCAS SSD =  0.05 (mean)

•  Maximum Performance Task- Apraxia Score:

     – CAS =  1.58 0.26 (mean)

     – nonCAS SSD = 0.73 0.26 (mean)

–  Were the groups similar? No  

–  Were the communication problems adequately described? No  

     •  disorder types:  Childhood Apraxia of Speech; Speech Sound Disorder without diagnosis of Childhood Apraxia of Speech

5.  What were the different conditions for this research?

•  Subject (Classification) Groups? Yes :

     – CAS

     – nonCAS SSD

•  Experimental Task? Yes 

     – Ps imitated recordings of 20 words consisting of 3 to 5 syllables

•  Criterion/Descriptive Conditions? Yes

Articulatory movements impacting segments

     – voicing change

     – lengthened vowels 

     – nasal changes

Phonological structure

     – percent structurally correct words

     – percent full syllable deletion 

     – migrations  

     – epenthesis 

     – percent full syllable addition 

     – lenitions  

     – metathesis 

Suprasegmentals

     – percent stress correct  

     – syllable segregation

Overall segmental accuracy

     – percent consonants correct 

     – percent phonemes correct 

     – percent vowels correct 

6.   Were the groups controlled acceptably? Yes 

7.  Were dependent measures appropriate and meaningful? Yes 

     – OUTCOME #1: voicing change 

     – OUTCOME #2: percent structurally correct words

     – OUTCOME #3: percent stress correct  

     – OUTCOME #4: percent full syllable deletion 

     – OUTCOME #5: percent consonants correct

     – OUTCOME #6: migrations 

     – OUTCOME #7: lengthened vowels 

     – OUTCOME #8: percent phonemes correct 

     – OUTCOME #9: percent vowels correct 

     – OUTCOME #10: epenthesis 

     – OUTCOME #11: nasal changes

     – OUTCOME #12: percent full syllable addition

     – OUTCOME #13: lenitions 

     – OUTCOME #14: metathesis 

     – OUTCOME #15: syllable segregation

• All the dependent measures were subjective.

• None of the dependent measures were objective.

8.  Were reliability measures provided?

  Interobserver for analyzers?  Yes. The investigators provided reliability data for transcribing of

          – segment accuracy (.97), 

          – segregated syllables (.83), and 

          – lexical stress deviations (.71).   

•  Intraobserver for analyzers?  No  _

•  Treatment or test administration fidelity for investigators?  NA 

9.  Description of design: 

• The investigation involved 2 questions. The first question involved a review of the literature in which over 190 features were identified as potentially being able to differentiate between children (7-17 years) with CAS and those with SSD but not CAS (nonCAS SSD).

• The investigators systematically reduced the original of list of features to 15 perceptual features. (Only of 2 these features were prosody related.) These 15 features were selected for involvement in question two.

• The purpose of the second question was to determine if children with CAS could be distinguished from children with nonCAS SSD. Using the 15 perceptual features, the investigators analyzed previously recorded productions on a multisyllable word repetition (MSWR) task of 61 children (CAS = 20; nonCAS SSD = 41) 

10.  What were the results of the statistical (inferential) testing?

• Because of multiple statistical comparisons, a correction was applied to the results of the inferential tests. Accordingly, the p values for comparisons that were labelled as significant ranged from .0004 to .0034.

• The following features were judged to be significantly different:

     – OUTCOME #1: voicing change

     – OUTCOME #2: percentage of structurally correct words

     – OUTCOME #3: percent stress correct

     – OUTCOME #4: percent full syllable deletion

•  What was the statistical test used to determine significance? Mann-Whitney U

•  Were effect sizes provided? Yes 

     – OUTCOME #1: voicing change  (derived Cohen’s d = 0.95, large)

     – OUTCOME #2: percentage of structurally correct words (derived Cohen’s d = 0.907, large)

     – OUTCOME #3: percent stress correct (derived Cohen’s d = 0.865, large)

     – OUTCOME #4: percent full syllable deletion (derived Cohen’s d = 0.74, moderate)

•  Were confidence interval (CI) provided?  Yes. For the most part no, but they were provided for reliability data.

11.  Summary of correlational results:   The investigators provided these data but they are not the focus of this review.

12.  Summary of descriptive results:  Qualitative research.  NA

13.  Brief summary of clinically relevant results:  

The investigators determined that the CAS and nonCAS SSD children’s performance on a MSWR task could be distinguished using 4 features: correct lexical stress, prevalence of voicing changes, percentage of structurally correct words, and syllable deletions. With respect to prosody, incorrect stress may continue through childhood for students diagnosed with CAS. 

ASSIGNED GRADE FOR QUALITY OF EXTERNAL EVIDENCE: NA, this is not an intervention study.

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McCabe et al. (2014)

February 24, 2021

EBP THERAPY ANALYSIS for 

Single Case Designs

NOTES:  

•  The summary of the intervention procedure(s) can be viewed by scrolling about two-thirds of the way down on this page.

Key:

 C =  Clinician

 CAS =  Childhood Apraxia of Speech

CTPP =  Comprehensive Test of Phonological Processing 

 EBP =  evidence-based practice

 KP =  used knowledge of performance 

 NA = not applicable 

 P =  Patient or Participant

 pmh =  Patricia Hargrove, blog developer

 PCC =  Percent Consonants Correct 

 PND =  Percentage of Nonoverlapping Data 

 PPVT = Peabody Picture Vocabulary Test 

 PVC =  Percent Vowels Correct

 ReST =  Rapid Syllable Transition Training

 SLP =  speech–language pathologist

 SS =  Standard Score

TAP =  Test of Auditory Processing

 WNL =  within normal limits 

SOURCE:  McCabe, P., Macdonald-D’Silva, A. G., van Rees, L., Ballard, K. J., & Arciuli, J. (2014).  Orthographically sensitive treatment for dysprosody in children with childhood apraxia of speech using ReST intervention. Developmental Neurorehabilitation, 17 (2), 137-146. DOI: 10.3109/17518423.2014.906002 

REVIEWER:  pmh

DATE: February 24, 2021

ASSIGNED OVERALL GRADE:  B+  The highest grade possible based on the design of this investigation is A-   (Single-case experimental design). The Assigned Overall Grade is not a judgment about the quality of the intervention; it is rating of the evidence presented in the investigation.

TAKE AWAY:  This investigation explored the effectiveness of Rapid Syllable Transition Training (ReST) on the production of lexical stress in the speech of 4 children diagnosed with Childhood Apraxia of Speech (CAS). Using an AB design, the investigators identified changes from pre- to post- treatment and retention, 4 weeks after the termination of the intervention. The findings suggest that lexical stress improved as the following the intervention and that the changes are maintained.

1.  What was the focus of the research?  Clinical Research  

2.  What type of evidence was identified?                              

–  What  type of single subject design was used? Single Subject Experimental Design with Specific Clients: AB 

  What was the level of support associated with the type of evidence?  Level = A-

3.  Was phase of treatment concealed?                                              

•  from participants?  No 

•  from clinicians?  No 

•  from data analyzers?  No 

4.  Were the participants (Ps) adequately described? Yes 

–  How many Ps were involved in the study?  4

–  CONTROLLED CHARCTERISTICS:    

•  expressive language: sample of at least 50 utterances

•  receptive language: within normal limits (WNL)

•  diagnosis: CAS

•  hearing level: WNL

•  comorbid developmental or genetic problems: excluded

•  oral motor skills: WNL for structure, strength, muscle tone, and reflexes

–  DESCRIBED CHARACTERISTICS:

•  age:  55 to 8-6

•  gender:  4m                                   

•  expressive language:

     – Clinical Evaluation of Language Fundamentals (4th ed; CELF) Expressive Language Index: Standard Score (SS) = 53-80

•  receptive language: 

     – Peabody Picture Vocabulary Test (PPVT):  SS = 90-117

     – CELF Receptive Language Index:  SS = 96-105

     – Test of Auditory Processing (3rd ed; TAP) Word Discrimination:  SS = 5-9

     – Test of Auditory Processing (3rd ed; TAP) Word Memory:  SS = 6-12

•  literacy:

     – Woodcock Reading Mastery Test-Revised Basic Skills Cluster:  SS = 88-127

     – Woodcock Reading Mastery Test-Revised Word Identification:  SS = 90-129

     – Woodcock Reading Mastery Test-Revised Word Attack:  SS = 81-121

     – Woodcock Reading Mastery Test-Revised Lower Case Letters Checklist percent: = 48-94

     – Comprehensive Test of Phonological Processing (CTPP) Phonological Awareness Composite Score:  SS = 64-106

     – CTPP Phonological Memory Composite Score:  SS = 70-91

     – CTPP Memory for Digits:  SS = 6-10

     – CTPP Non-word Repetition Score:  SS = 4-9

     – CTPP Rapid Naming Composite Score:  SS = 91-136

     – Neale Analysis of Reading Ability (3rd ed; NARA-3)

          ∞ Accuracy: Reading Age  <6 – 7.7 years

          ∞ Comprehension: Reading Age  6.3 to 7.5 years

          ∞ Rate: Reading Age  6.8 – >13

–  Were the communication problems adequately described? Yes

•  Disorder type: Childhood Apraxia of Speech

5.  Was membership in treatment maintained throughout the study?  Yes 

•  If there was more than one participant, did at least 80% of the participants remain in the study?  Yes 

6.  Did the design include appropriate controls?  Yes 

•  Were baseline/preintervention data collected on all behaviors?  Yes

  Did probes/intervention data include untrained stimuli?  Yes 

•  Did probes/intervention data include trained stimuli?  Yes 

•  Was the data collection continuous?  Yes_x__, for several of the outcomes.  

•  Were different treatment counterbalanced or randomized?  NA  

7.  Were the outcome measures appropriate and meaningful? 

•  OUTCOME #1: Prosodic (lexical stress) accuracy of targeted bisyllable pseudo words during treatment sessions

•  OUTCOME #2: Segmental accuracy of targeted bisyllable pseudo words during treatment sessions

•  OUTCOME #3: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of trained targets

•  OUTCOME #4: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of untrained targets

•  OUTCOME #5: Percent Vowels Correct (PVC) in connected speech

•  OUTCOME #6: Percent Consonants Correct (PCC) in connected speech

•  OUTCOME #7: Percent correct stress patterns in connected speech

•  OUTCOME #8: PPVT Standard Score (this was a foil outcome; that is, improvement was not expected)

–  All of the outcomes that were subjective.

–  None of the outcomes were objective.

–  RELIABILITY DATA:

•  Inter-rater reliability of accuracy (stress and segmental) of clinician’s (C’s) judgment of participant’s (P’s) productions: 88%

•  Intra-rater reliability of accuracy (stress and segmental) of C’s judgment of P’s productions: 93%

•  Inter-rater reliability of phonemic transcriptions: 83% to 90%

•  Intra-rater reliability of phonemic transcriptions: 95% to 97%

  Treatment fidelity: 75% to 83% (errors tended to be related to delaying feedback

8.  Results:

–  Did the target behavior(s) improve when treated?  Yes, for the most part, but none of the Ps in this investigation achieve Mastery in the 12 sessions.

–  DESCRIPTION OF RESULTS

•  OUTCOME #1: Prosodic (lexical stress) accuracy of targeted bisyllable pseudo words during treatment sessions: Strong Improvement

     ∞ P1 = baseline = below 10%; final session = 66%   

     ∞ P2 = baseline = below 30%; final session = 82%   

     ∞ P3 = baseline = 15%; penultimate session = 75%

     ∞ P4 = baseline = around 30%; final 3 sessions = averaged 79%

•  OUTCOME #2: Segmental accuracy of targeted bisyllable pseudo words during treatment sessions:  Moderate to strong improvement

     ∞ P1 = baseline = below 10%; final session = 66%   

     ∞ P2 = baseline = below 10%; final 3 sessions = 39% to 59%   

     ∞ P3 = baseline = about 50%; penultimate session = 75%

     ∞ P4 = baseline = around 50%; final 3 sessions = averaged 79%   

•  OUTCOME #3: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation)  of trained targets: Moderate improvement

     ∞ P1 = baseline =  0%       ; final probes = 10%; retention probe = 50-60%

     ∞ P2 = baseline =  0%; final probe = about 40%; retention probe = about 30%

     ∞ P3 = baseline = 20% or under; final probe = about 50%; retention probe= about 40%

     ∞ P4 = baseline = about 20%; final probe = about 40%; retention probe = about 40%

•  OUTCOME #4: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of untrained targets: Limited improvement

     ∞ P1 = baseline =   0%; final probe = 0%; retention probe = under 20%

     ∞ P2 = baseline = under 10%; final probe = about 30%; retention probe = 0%

     ∞ P3 = baseline = 20% or under; final probe = about 30%; retention probe = about 30%

     ∞ P4 = baseline = 0% to 40%; final probe = about 20%; retention probe = about 40%. 

•  OUTCOME #5: Percent Vowels Correct (PVC) in connected speech: Limited improvement

     ∞ P1 = pretreatment = 74%; post treatment = 81%; retention = 80%      

     ∞ P2 = pretreatment = 78%; post treatment = 87%; retention = 87%      

     ∞ P3 = pretreatment = 90%; post treatment = 88%; retention = 92%

     ∞ P4 = pretreatment = 85%; post treatment = 84%; retention = 91%

•  OUTCOME #6: Percent Consonants Correct (PCC) in connected speech:  Limited improvement to ineffective

     ∞ P1 = pretreatment = 81%; post treatment = 80%; retention = 54%

     ∞ P2 = pretreatment = 95%; post treatment = 95%; retention = 88%

     ∞ P3 = pretreatment = 70%; post treatment = 86%; retention = 74%

     ∞ P4 = pretreatment = 60%; post treatment = 70%; retention = 66%

•  OUTCOME #7: Percent correct stress patterns in connected speech: Limited to moderate improvement

     ∞ P1 = pretreatment = 46%; post treatment = 43%; retention = 70%

     ∞ P2 = pretreatment = 53%; post treatment = 81; retention = 76%      

     ∞ P3 = pretreatment = 79%; post treatment = 77%; retention = 85%     

     ∞ P4 = pretreatment = 64%; post treatment = 68%; retention = 83%     

•  OUTCOME #8: PPVT Standard Score (this was a foil outcome; that is, improvement was not expected) Ineffective

     ∞ P1 = pretreatment = 90; post treatment = 84   

     ∞ P2 = pretreatment = 90; post treatment = 96   

     ∞ P3 = pretreatment = 91; post treatment = 90   

     ∞ P4 = pretreatment = 117; final session = 119  

9.  Description of baseline: 

–  Were baseline data provided?  Variable

  Was baseline low (or high, as appropriate) and stable?

•  OUTCOME #3: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation)  of trained targets: Baseline low and stable for all P

•  OUTCOME #4: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of untrained targets: Baseline was low and stable for Ps 1, 2, and 3 but not 4.

  Was the percentage of nonoverlapping data (PND) provided? 

Yes  _____  No  ________  Only for the following Outcome-

•  OUTCOME #3: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of trained targets: 

     – PND for P1 = 75% (fairly effective)

     – PND for P2 = 100% (highly effective)

     – PND for P3 = 75% (fairly effective)

     – PND for P4 = 100% (highly effective)

•  OUTCOME #4: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of untrained targets: 

     – PND for P1 = 25% (unreliable/ineffective)

     – PND for P2 = 25% (unreliable/ineffective)

     – PND for P3 = 75% (fairly effective)

     – PND for P4 = 0% (unreliable/ineffective)

10.  What is the clinical significance?  NA

11.  Was information about treatment fidelity adequate?  Yes. The investigators calculated treatment fidelity for each of the Ps. It ranged from 75% to 83% with errors tending to be related to delaying feedback.

12.  Were maintenance data reported?  Yes. Four weeks after the post treatment assessments, retention was measured for selected outcomes. The amount of retention varied based on the outcome and individual Ps.

     – OUTCOME #3: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation)  of trained targets

     ∞ Strong retention for P1and P4.

     ∞ Moderate retention for P2 and P3 

     – OUTCOME #4: Percent perceptual accuracy (target perceived as having both correct prosody and correct articulation) of untrained targets:

     ∞ Limited retention P4 

     ∞ Strong retention P4 (perhaps P1

     ∞ Failure to retain P2  

•  OUTCOME #5: Percent Vowels Correct (PVC) in connected speech

     ∞ all Ps strong 

•  OUTCOME #6: Percent Consonants Correct (PCC) in connected speech

     ∞ Failure –retention was markedly lower than pretreatment  for P1 

     ∞ Strong retention (P2)

     ∞ Limited retention (P3, P4)  

•  OUTCOME #7: Percent correct stress patterns in connected speech:

     ∞ Strong retention (all Ps)

13.  Were generalization data reported? Yes

•  There were 3 types of generalization data: 

     – performance on trained verse untrained probes at selected intervals (baseline and probes), 

     – performance in connected speech, 

     – performance on the PPVT before and after treatment. 

•  Performance on trained verse untrained probes at selected intervals (baseline and intervention probes): The percent overall accuracy of trained and untrained targets during baseline was similar for all Ps. However, the percent overall accuracy of trained targets exceeded baseline for all Ps for intervention probes. 

•  All Ps increased their percent of correct stress in connected speech during retention testing, although connected speech was not targeted during treatment.

•  None of the Ps increased their PPVT scores from the beginning to the end of treatment. This was not expected because this was considered to be a foil measure.

14.  Brief description of the design:

• The authors provided supplementary data online in addition to the information in the Results section. Only the data presented in the article are described in this review.

• The investigators administered ReST to 4 children who had been diagnosed with CAS. performance in connected speech.

• The investigators measured selected outcomes at a series of 3 baseline and 3 probe sessions as well at a retention session, 4 weeks following treatment. Other outcomes were measured before and after treatment.

• The analysis of the data included visual analysis as well as the calculation of PND.

ASSIGNED OVERALL GRADE OF THE QUALITY OF SUPPORT FOR THE INTERVENTION:  B+

SUMMARY OF INTERVENTION

PURPOSE: To explore the effectiveness of ReST in improving the production of lexical stress

POPULATION:  Childhood Apraxia of Speech (CAS); children

MODALITY TARGETED:  production

ELEMENTS/FUNCTIONS OF PROSODY TARGETED:  lexical stress

ELEMENTS OF PROSODY USED AS INTERVENTION:  stress, duration, rate

OTHER ASPECTS OF LANGUAGE/COMMUNICATION TARGETED:  articulation 

OTHER TARGETS:  a foil target of receptive vocabulary 

DOSAGE:  60 minute individual sessions, 4 sessions per week for 3 weeks (12 sessions); homework was not assigned.

ADMINISTRATOR:  SLP

STIMULI: pseudowords 

MAJOR COMPONENTS:

• The focus of ReST is the production of bisyllable nonsense words with stress patterns (Strong-Weak, SW, or Weak-Strong, WS). Because previous research has indicated that even children as young as 5 (the youngest P in this investigation) have a tendency to produce certain pseudo words as SW or WS, the tendencies were adhered to in the construction of pseudowords for the targets and probe stimuli. 

• Treatment session consisted of pre-practice (10-20 minutes) and practice (40-50 minutes) phases.

PRE-PRACTICE PHASE 

• In place of the terms Weak and Strong, the clinician (C) used Short and Long. 

• C presented a bisyllable pseudoword target to the participant (P) randomly and asked P to identify the pseudoword as Long-Short or Short-Long.

• C corrected P if the wrong stress pattern was identified.

• C then modeled the target word and requested P to produce it. 

• C provided 100% feedback regarding the accuracy of the stress pattern produced by P. If P’s production of stressing was in error, C used knowledge of performance (KP) feedback and described how P should modify the production (e.g., “Try to make the first part even shorter”, p 140).

• C was also allowed to provide other cues such as hand clapping or shaping to facilitate correct production.

• Regarding the segmental accuracy of the target (not the primary focus of this investigation), C provided knowledge of results (KR) feedback. That is C only indicated whether the speech sound production was correct or incorrect.

• When P produced 5 correct consecutive trials, C proceeded to the Practice Phase

PRACTICE PHASE

• C presented the treatment targets (19 bisyllable pseudo words) in random order within sets to allow for the production of at least 100 pseudowords per session. 

• Depending on the P’s reading level, P either read aloud a pseudoword or imitated C’s production of the C reading aloud the pseudoword.

• Three to 5 seconds after P’s attempt, C provided KR feedback on the combined prosodic and segmental accuracy at the 50% level.

• Mastery was defined as 80% correct performance over 3 consecutive sessions. (Typically developing children can achieve this in 3 to 4 sessions.) None of the Ps in this investigation achieve Mastery in the 12 sessions.

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