A longitudinal study of the emergence of phonemes in children with Down syndrome.

Articulation norms are typically used to measure sound acquisition and mastery in children with Down syndrome. The present longitudinal study examines the clinical records of 60 children with Down syndrome to evaluate phoneme acquisition and emergence. Results document the order of emergence of sounds in children with Down syndrome. Factors affecting emergence of sounds (e.g. oral motor skills) and difficulties in using a mastery model to evaluate speech sound acquisition in children with Down syndrome are explored. Clinical as well as research implications of the data are presented.