Benway & Preston (2020)


Comparison/Nonintervention Research 


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.


DATE: January 29, 2022


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  


•  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


•  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 


     – 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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