Table 6.

Charting of CAS studies in impaired linguistic–motor processes category.

Study	Participants			Method/task	Dependent measures	Main results	Sensitivity/specificity?
	Group	n	Age range (years/years;months)
Nijland, Maassen, & van der Meulen, (2003)	CAS	5	5;0–6;10	Acoustic measures; phrase repetition under normal speaking and bite block conditions	- F2 trajectory	- Bite block did not affect anticipatory coarticulation for TD and healthy adult speakers, but had large effect on coarticulation for children with CAS, suggesting motor planning difficulty	N
	TD	5	5;0–6;10
	HC	6	20–30
Peter & Stoel-Gammon (2008)	sCAS a	11	4;7–6;6	Acoustic measures, behavioral rating; nonword imitation, rhythm imitation	- % accuracy in imitation, vowel duration, rate	- Low timing accuracy was associated with a high number of CAS characteristics	N
	TD	11	4;10–6;9
Froud & Khamis-Dakwar (2012)	CAS	5	5;1–8;3	EEG; oddball paradigm with syllables	- Mismatch negativity (MMN) responses	- CAS group showed different MMN responses to allophonic and phonemic contrasts than the TD group, suggesting phonological involvement in CAS	N
	TD	5	5;3–8;9
Shriberg et al. (2012)	CAS	40	5;0–50;0	Nonword repetition (syllable repetition task [SRT])	- SRT scores: encoding (% substitution errors within manner class), transcoding (additions), memory (greater difficulty with increasing length)	- CAS group had lower SRT scores in multiple domains (encoding, transcoding, and memory) compared to controls	N
	TD	119	3;0–7;0+
	SD	140	3;0–7;0+
	SD + LI	70	3;0–7;0+
Preston et al. (2014)	CAS	8	9;0–15;0	EEG; monosyllabic and multisyllabic word production	- Event-related potentials (ERPs)	- CAS group had reduced ERP amplitude of signal reflecting phonological encoding while saying multisyllabic words relative to monosyllabic words	N
	TD	13	9;0–15;0
Iuzzini-Seigel et al. (2015)	CAS	9	6;1–17;6	Acoustic measures; nonword repetition with and without auditory masking	- Voice onset time and vowel space area	- Auditory masking only affected speech of children with CAS, suggesting overreliance on auditory feedback in CAS	N
	SD	10
	TD	11
Shriberg et al. (2017c)	CAS	37	4;0–23;0	Acoustic measures, phonetic transcription, prosody-voice coding; syllable repetition, conversational speech	- PM scores, SRT scores, and percentage consonants correct	- Findings support the presence of deficits in both encoding and transcoding of phonemic representations in CAS	N
	AOS	22	45;0–84;0
	SD	205	3;0–9;0
Zuk et al. (2018)	CAS	7	4;7–17;3	Behavioral response: same–different judgments of /da/–/ga/ stimuli	- Discrimination threshold, /da/–/ga/ F3 onset frequency	- CAS-only group showed no speech perception differences from TD group; all LI groups showed poorer syllable discrimination than non-LI groups	N
	CAS + LI	6	5;4–12;4
	LI	7	7;8–12;0
	SD	12	6;4–9;11
	TD	15	7;10–16;9
Ingram et al. (2019)	CAS	9	5;0–6;11	Behavioral response: detection of vowel duration differences	- % accuracy in making same–different judgments regarding vowel length	- Children with CAS exhibited deficits in detecting vowel duration differences compared to TD group, suggesting possible perceptual component	N
	TD	14	5;0–6;11

Note. CAS = childhood apraxia of speech, developmental apraxia of speech, speech disorder–developmental apraxia of speech (sCAS = suspected childhood apraxia of speech); F2 = second formant; N = no; TD = typically developing; HC = healthy control; EEG = electroencephalography; SD = speech sound disorder, phonological disorder, articulation disorder, multiple phonological disorder; LI = language impairment; PM = Pause Marker; AOS = acquired apraxia of speech; F3 = third formant.

^asCAS in this study was children with severe speech sound disorders who exhibited between 4 and 9 speech characteristics of CAS.