Single-Word Speech Intelligibility in Children and Adults With Down Syndrome.

Purpose: A single-word identification test was used to study speech production in children and adults with Down syndrome (DS) to determine the developmental pattern of speech intelligibility with an emphasis on vowels.

Method: Speech recordings were collected from 62 participants with DS aged 4-40 years and 25 typically developing participants aged 4-7 years. Panels of 5 adult lay listeners transcribed the speech recordings orthographically, and their responses were scored in comparison with the speakers' target words.