Onset of speech-like vocalizations in infants with Down syndrome.

Canonical babbling of infants with and without Down syndrome was compared. Infants with Down syndrome and typically developing infants began canonical babbling in the first year of life, but the infants with Down syndrome began 2 months later. Once begun, their canonical babbling was less stable than that of typically developing infants. Age at onset of canonical babbling for the infants with Down syndrome was correlated with their scores at 27 months of age on the Early Social-Communication Scales. The results of this study suggest that Down syndrome influences vocal development in the first year of life and that early vocal development is related, possibly in combination with motoric and cognitive factors, to later social and communicative functioning of children with Down syndrome.