Predictors of Speech Ability in Down Syndrome
Phase: NA
Conditions: Speech Intelligibility Intervention in Down Syndrome
Sponsor: Vanderbilt University Medical Center

Version 6: 6/20/2025 
 
 
 
 
 
 
 
 
Predictors of Speech Ability in Down Syndrome 
Protocol 
NCT05016037 
June 20, 2025 
 

Version 6: 6/20/2025 
Protocol 
Eighteen children with Down Syndrome were recruited to parJcipate in this study. Sixteen 
children with Down Syndrome parJcipated in the full assessment and Speech Enrichment 
sessions detailed below. Two dropped out due to logisJcs, being unable to aMend all the 
sessions. There were no adverse events. 
Assessments 
ParJcipants were asked to aMend assessment sessions at the beginning and again at the end of 
the enrollment in the study, which occurred over approximately six months. Assessments took 
place over 1-2 visits and lasted ~2-6 hours. Assessments were completed in a 10 X 12 room on 
the 10th ﬂoor of the Bill Wilkerson Center, remotely, or, if the parent wished, in their home in a 
quiet room at a table. The Wilkerson Center includes a standard tesJng room that includes a 
table and some chairs. Assessment sessions were audio and video recorded. 
Standardized tests 
Note: These are copyrighted tests and so items cannot be reproduced. The following synopses 
include links to publishers’ websites so that reviewers can access the descrip@ons. Note that 
none of the tests measure psychiatric condi@ons, mental health, or other sensi@ve diagnos@c 
categories (e.g. drug addic@on) and so DO NOT include ques@ons about violence, illegal drug 
use or other sensi@ve content. Rather, these tests include naming and poin@ng to pictures of 
common objects and ac@ons (e.g., point to “car,” point to “running,” “what is this?” when 
presented with a picture of a house). 
The following tests are part of rou$ne educa$onal tes$ng for people with Down syndrome and 
were administered by a trained speech language pathologist. 
Recep@ve One-Word Vocabulary Test-fourth edi@on 
(hMps://www.pearsonassessments.com/store/usassessments/en/Store/Professional-
Assessments/S peech-%26-Language/RecepJve-and-Expressive-One-Word-Picture-Vocabulary-
Tests-%7C-Fourth- 
EdiJon/p/100000338.html) 
This test requests that the parJcipant point to a picture from an array of four and is designed to 
measure comprehension of single words. Items include common nouns and verbs. 
The scores for this test include number of items correct (raw score) and standard scores. The 
raw score is the number of correct responses out of a total of 190 items. A lower score means 
fewer correct responses so that a lower score means poorer performance. The raw score is used 
to generate a standard score, which indexes a child’s performance to same age peers. Standard 
scores have a mean of 100 and a standard deviaJon of 15. A low score (e.g., 71) means 
relaJvely poorer performance as compared to same age peers, a higher score (e.g., 122) means 
relaJvely beMer performance relaJve to same age peers. A score of 85 to 115 is generally 
considered to be within a typical range.   

Version 6: 6/20/2025 
Expressive One-Word Vocabulary Test-fourth edi@on 
(hMps://www.pearsonassessments.com/store/usassessments/en/Store/Professional-
Assessments/S peech-%26-Language/RecepJve-and-Expressive-One-Word-Picture-Vocabulary-
Tests-%7C-FourthEdiJon/p/100000338.html) 
This test requests that the parJcipants name individually presented pictures and is designed to 
measure producJon of single words (expressive vocabulary). Each picture depicts common 
nouns and verbs. The scores for this test include number of items correct (raw score) and 
standard scores. The raw score is the number of correct responses out of a total of 190 items. A 
lower score means fewer correct responses so that a lower score means poorer performance. 
The raw score is used to generate a standard score, which indexes a child’s performance to 
same age peers. Standard scores have a mean of 100 and a standard deviaJon of 15. A low 
score (e.g., 71) means relaJvely poorer performance as compared to same age peers, a higher 
score (e.g., 122) means relaJvely beMer performance relaJve to same age peers. A score of 85 
to 115 is generally considered to be within a typical range.   
Woodcock Camarata Ar@cula@on BaTery 
(hMps://www.schoolhouseeducaJonalservices.com/woodcock-camarata-arJculaJon-baMery/) 
This test requests that the parJcipant name a picture of common nouns and the speech 
producJon accuracy (number of speech errors) is recorded. If they do not know the picture, the 
examiner names the item and asked that the child imitates the word. This standardized test 
measures pronunciaJon ability and are rouJnely administered to children with Down 
syndrome. The scores for this test include number of speech errors (raw score) and standard 
scores. Few errors yield a beMer (higher) score. The raw score is the number of correct 
responses. The raw score is used to generate a standard score, which indexes a child’s 
performance to same age peers. Standard scores have a mean of 100 and a standard deviaJon 
of 15. A low score (e.g., 71) means relaJvely poorer performance as compared to same age 
peers, a higher score (e.g., 122) means relaJvely beMer performance relaJve to same age peers. 
A score of 85 to 115 is generally considered to be within a typical range.   
Arizona Ar@cula@on and Phonology Scale, fourth revision (Arizona-4) 
hTps://www.wpspublish.com/arizona-4-arizona-ar@cula@on-and-phonology-scale-fourth-
revision 
This test requests that the parJcipant names, repeats or reads sJmulus content. If they do not 
know the picture, the examiner names the item and asked that the child imitate the word. This 
standardized test measures pronunciaJon ability and are rouJnely administered to children 
with Down syndrome. For this study, the number of correct phonemes produced correctly was 
divided by the total number of phonemes in the test. This is the number of correct phonemes 
divided by the number of total phonemes divided by 100. A higher number means beMer 
speech producJon whereas a lower number shows poorer speech ability. 
Leiter Interna@onal Performance Scale-third edi@on. hMps://www.wpspublish.com/leiter-3-
leiter-internaJonal-performance-scale-third-ediJon 
This is a standardized assessment of nonverbal cogniJve ability and includes picture matching, 
and looking at and compleJng a visual sequence using pictures. As am example, the examinee is 

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presented with a picture of a hand and another with a glove. The examiner points to each photo 
and then presents a picture of a foot. A set of pictures, including a shoe, a hat, and a spoon is 
presented. The examinee then selects the picture that goes with the foot (shoe). The scores for 
this test include the number of items correct (raw score) and standard scores, with a mean of 
100 and a standard deviaJon of 15. A low score (e.g., 71) means relaJvely poorer performance 
as compared to same age peers, a higher score (e.g., 122) means relaJvely beMer performance 
relaJve to same age peers. A score of 85 to 115 is generally considered to be within a typical 
range.   
15 Minute Spontaneous speech and language sample 
This is a play-based conversaJon sample wherein the parJcipant talks with the examiner about 
toys and picture books. The focus of the interacJon is on the child's preferred acJviJes, so the 
parJcipant is allowed to select the toys and books they wish to talk about. These speech and 
language samples were video and audio recorded and subsequently transcribed for speech, and 
for length of uMerance. This sampling is rouJnely performed by speech language pathologist as 
a part of standardized speech and language assessments. For this study, the number of correct 
phonemes produced correctly in the sample was divided by the total number of phonemes in 
the overall sample (which was phoneJcally transcribed). Percent correct was the number of 
correct phonemes divided by the number of total phonemes divided by 100. A higher number 
means beMer speech producJon whereas a lower number shows poorer speech ability. 
Speech Enrichment Sessions 
Sedng, Materials and AcJviJes 
ParJcipants were asked to aMend speech enrichment sessions twice per week during the study, 
for a period of four months. Sessions were completed in a 10 X 12 room on the 10th ﬂoor of the 
Bill Wilkerson center, remotely, or at the parJcipants home and were scheduled at the family’s 
convenience. The sedng at Bill Wilkerson Center is a standard room that includes a table and 
some chairs. Sessions at home were completed in a living room or family room of the family’s 
choice. Speech enrichment sessions were audio and video recorded. 
The materials were similar to those in the language sampling sessions and included toys and 
books. The acJviJes included spontaneous verbal interacJons while playing the toys and/or 
talking about books. These can include typical play rouJnes and scenarios (e.g. toy school 
house, toy zoo) and picture books (e.g. where the wild things are, goodnight moon). 
Procedures 
The examiner engages the child with Down Syndrome in a play based conversaJon wherein the 
child is encouraged to talk about the toys and books. The focus of the enrichment sessions is on 
delivering an immediate lexical (word) response with correct phonemes to a child’s producJon 
that contained incorrect phoneme producJon using verbal transacJons. That is, a child’s 
spontaneous or elicited producJon containing phonological errors was immediately followed 
with a clinician model that corrected the error(s) at the word level rather than the isolated 

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phoneme level. As an example, a speech recast of child’s producJon of the word bake as [be] 
would be the whole lexeme bake [bek] rather than producJon drill on [k] in isolaJon. Clinicians 
were taught to use at least two speech recasts per minute (which has been feasible in previous 
studies with DS). A successful recast was delivered when (a) the child talks and (b) the child’s 
intended message is understood. To enhance the probability that children would use a suﬃcient 
number of plaiorm uMerances that clinicians could suﬃciently understand to provide accurate 
speech recasts, clinicians used verbal rouJnes and topic-conJnuing quesJons. Verbal rouJnes 
and topic-conJnuing quesJons increase child talking. In addiJon, the predictability of the 
content in spoken turns in these rouJnes provides suﬃcient listener support for interpreJng the 
child’s communicaJve message, despite poor speech accuracy. Also, clinicians using the lexical 
recast intervenJon were trained not to use elicited imitaJon prompts when delivering lexical 
recasts during speech enrichment sessions.