Investigation of the articulatory patterns of young adults with Down syndrome using electropalatography

Tongue movements for speech in three adults with Down syndrome and one normal speaking control were investigatedusing electropalatography (EPG) and diadochokinetic rate (DDK)techniques. The subjects with Down syndrome all showedsubstantially larger areas of tongue-palate contact comparedwith the control subject for alveolar sounds /t, d, n, l/, anddifferences in fricative articulation. Undershoot (incompleteclosure) was a feature of velar articulations /k, g/ in the subjectswith Down syndrome. Longer closure duration, longer consonanttransition times within clusters and consistently slower DDKrates were also noted. Asymmetry and variabilitywere evident in two of the subjects with Down Syndrome.The results support the hypothesis that people with Downsyndrome have difficulties with coordinating the rapid tonguemovements necessary for clear speech with impaired tonguemotility and motor programming as well as phonological delay.Implications for treatment are discussed.