Estimates of the prevalence of speech and motor speech disorders in adolescents with Down syndrome

Figures & data

Table 1. Estimates of the interjudge and intrajudge agreement for phonetic transcription, prosody-voice coding, and acoustic analyses.

	Agreement Types
Data	Interjudge	Intrajudge	No. of Tokens Analyzed	Variable	Average Percentage of Agreement
Phonetic Transcription	X			Consonants
			901 Utterances; 1977 Words	Broad	93.3
				Narrow	74.0
				Vowels
				Broad	85.8
				Narrow	73.0
		X		Consonants
			901 Utterances; 1996 Words	Broad	94.1
				Narrow	78.0
				Vowels
				Broad	87.9
				Narrow	74.9
Prosody-Voice Coding	X		234 Utterances	Appropriate- Inappropriate	87.2
		X		Appropriate- Inappropriate	91.1
Acoustic Analyses	X			Phoneme Duration
			152 Consonants	Consonants	84.5
			784 Vowels	Vowels	85.8
		X		Phoneme Duration
			150 Consonants	Consonants	89.0
			783 Vowels	Vowels	87.1
	X			Vowel Frequency
			793 Vowels	F0	97.9
			142 Vowels	F1	91.2
			144 Vowels	F2	95.2
		X		Vowel Frequency
			792 Vowels	F0	98.1
			157 Vowels	F1	91.1
			156 Vowels	F2	95.0
	X			Pause Variables
			170 Pauses	Pause – Non-Pause	94.1
			160 Pauses	Appropriate – Not Appropriate	77.5
			28 Pauses	Type 1 – Type 2	78.6
		X		Pause Variability
			170 Pauses	Pause – Non-Pause	91.2
			155 Pauses	Appropriate – Not Appropriate	61.3
			36 Pauses	Type 1 – Type 2	80.6

Table 2. Description of 45 participants with Down syndrome.

Variable	n	%	M	SD	Minimum	Maximum
Demographic
Chronological Age (yrs.)	45		14.2	2.3	10.0	20.0
% Male	45	55.6
Intelligence
IQ Composite^a	15		47.4	5.3	40	57
Intelligence Quotient^b	27		40.3	5.5	36	50
Language
Average Words per Utterance	45		4.6	1.9	1.9	9.3
Oral Composite^c	14		42.6	4.4	40	56
Speech
Percentage of Consonants Correct	45		78.9	8.7	59.3	93.3
Percentage of Vowels Correct	45		89.9	4.3	77.7	96.7
Intelligibility Index (%)^d	45		81.3	12.3	50.1	99.0

^a Standard scores for IQ Composite: Kaufman Brief Intelligence Test – Second Edition; Kaufman and Kaufman (2004).

^b IQ Scores: Stanford-Binet-4^th Edition; Thorndike et al. (1986).

^c Standard scores for Oral Composite: Oral and Written Language Scales (OWLS); Carrow-Woolfolk (1995).

^d Shriberg (1993).

Figure 1. Estimates of the prevalence of speech and motor speech disorders in adolescents with Down syndrome.

Figure 2. Estimates of the prevalence of five subtypes of dysarthria in adolescents with Down syndrome. The solid filled bars in Figure 2a are the mean percentage score findings for the 27 participants on the five dysarthria subtype indices described in the Supplement. The diagonal filled bars in Figure 2b are the mean percentile score findings for the same speakers on the five indices.

Table A1. The five Speech classifications and five Motor Speech classifications in the SDCS are each mutually exclusive. The five dysarthria subtype classifications are not mutually exclusive. That is, a speaker can meet percentile criteria for more than one of the five listed dysarthria subtype classifications (i.e., mixed dysarthria). See Supplement for the procedures and measures used to classify each motor speech disorder.

SDCS Classifications andDysarthria Subtypes	Abbreviation	Age (yrs;mos) at Assessment	Description	References^a
Five Speech Classifications
Normal(ized) Speech Acquisition	NSA	3–80	Does not meet criteria for any of the four Speech Disorder classifications	2, 3, 4
Speech Errors	SE	6–8;11	Age-inappropriate speech sound distortions	3, 4
Persistent Speech Errors	PSE	9–80	Age-inappropriate speech sound distortions that persist past 9 years of age	4, 5
Speech Delay	SD	3–8;11	Age-inappropriate speech sound deletions and/or substitutions	3, 4
Persistent Speech Delay	PSD	9–80	Age-inappropriate speech sound deletions and/or substitutions that persist past 9 years of age	3, 4, 5
Five Motor Speech Classifications
No Motor Speech Disorder	No MSD	3–80	Does not meet criteria for any of the four Motor Speech Disorders classifications	2, 6, 8
Speech Motor Delay	SMD	3–80	Meets PSI criterion for SMD	2, 6, 8
Childhood Dysarthria	CD	3–80	Meets DI and DSI criteria for CD	2, 6, 8
Childhood Apraxia of Speech	CAS	3–80	Meets PM criterion for CAS	6, 7, 8
Childhood Dysarthria & Childhood Apraxia of Speech	CD & CAS	3–80	Meets SDCS criteria for CD & CAS	2, 6, 8
Five Dysarthria Subtypes
Ataxic		3–80	Cerebellar disorder	1, 2
Spastic		3–80	Upper motor neuron disorder	1, 2
Hyperkinetic		3–80	Basal ganglia disorder; increased movement	1, 2
Hypokinetic		3–80	Basal ganglia disorder; decreased movement	1, 2
Flaccid		3–80	Lower motor neuron disorder	1, 2

Notes: PSI = Precision-Stability Index; DI = Dysarthria Index; DSI = Dysarthria Subtype Index; PM = Pause Marker.

^a 1. Duffy (2013); 2. Mabie and Shriberg (2017); 3. Shriberg (1993); 4. Shriberg, Austin, Lewis, McSweeny, and Wilson (1997); 5. Shriberg et al. (2010a); 6. Shriberg and Mabie (2017); 7. Shriberg et al. (2017); 8. Tilkens et al. (2017).

Kaufman, A. S., & Kaufman, N. L. (2004). Kaufman Brief Intelligence Test (2nd ed.). Circle Pines, MN: American Guidance Service.

 Google Scholar

Thorndike, R. L., Hagen, E. P., & Sattler, J. M. (1986). Stanford-Binet Intelligence Scale, 4th edition. Chicago, IL: Riverside.

 Google Scholar

Carrow-Woolfolk, E. (1995). Oral and Written Language Scales (OWLS). Bloomington, MN: Pearson Assessment.

 Google Scholar

Shriberg, L. D. (1993). Four new speech and prosody-voice measures for genetics research and other studies in developmental phonological disorders. Journal of Speech and Hearing Research, 36, 105–140.

 PubMedGoogle Scholar

Duffy, J. R. (2013). Motor speech disorders: Substrates, differential diagnosis, and management (3rd ed.). St. Louis, MO: Mosby.

 Google Scholar

Mabie, H. L., & Shriberg, L. D. (2017). Speech and motor speech measures and reference data for the Speech Disorders Classification System (SDCS). (Technical Report No. 23). Phonology Project, Waisman Center, University of Wisconsin-Madison. Retrieved from Phonology Project website: http://www.waisman.wisc.edu/phonology/

 Google Scholar

Shriberg, L. D., Austin, D., Lewis, B. A., McSweeny, J. L., & Wilson, D. L. (1997). The Speech Disorders Classification System (SDCS): Extensions and lifespan reference data. Journal of Speech, Language, and Hearing Research, 40, 723–740.

 PubMed Web of Science ®Google Scholar

Shriberg, L. D., Fourakis, M., Hall, S., Karlsson, H. B., Lohmeier, H. L., McSweeny, J., … Wilson, D. L. (2010a). Extensions to the Speech Disorders Classification System (SDCS). Clinical Linguistics & Phonetics, 24, 795–824.

 PubMed Web of Science ®Google Scholar

Shriberg, L. D., & Mabie, H. L. (2017). Speech and motor speech assessment findings in eight complex neurodevelopmental disorders. (Technical Report No. 24). Phonology Project, Waisman Center, University of Wisconsin-Madison. Retrieved from Phonology Project website: http://www.waisman.wisc.edu/phonology/

 Google Scholar

Shriberg, L. D., Strand, E. A., Fourakis, M., Jakielski, K. J., Hall, S. D., Karlsson, H. B., … Wilson, D. L. (2017). A diagnostic marker to discriminate of Childhood Apraxia of Speech from Speech Delay: I. Development and description of the Pause Marker. Journal of Speech, Language, and Hearing Research, 60, S1096–S1117.

 PubMed Web of Science ®Google Scholar

Tilkens, C. M., Karlsson, H. B., Fourakis, M., Hall, S. D., Mabie, H. L., McSweeny, J., … Shriberg, L. D. (2017). A diagnostic marker to discriminate childhood apraxia of speech (CAS) from Speech Delay (SD). (Technical Report No. 22). Phonology Project, Waisman Center, University of Wisconsin-Madison. Retrieved from Phonology Project website: http://www.waisman.wisc.edu/phonology/

 Google Scholar