Smith B L, Oller D K
J Speech Hear Disord. 1981 Feb;46(1):46-51. doi: 10.1044/jshd.4601.46.
Pre-meaningful vocalizations produced by nine normally developing and 10 Down's syndrome infants were recorded as part of a longitudinal study of language development. The recordings were phonetically transcribed using a modified version of the International Phonetic Alphabet. Data were analyzed in terms of (1) age at onset of reduplicated babbling (2) developmental trends for place of consonant articulation, and (3) developmental aspects of vocalic productions. In general, substantial similarities between the two groups of infants were observed with regard to the selected parameters. Both groups began to produce canonical, reduplicated babbling at 8-8 1/2 months of age, and trends regarding consonantal and vocalic development for the two groups were very similar during approximately the first 15 months of life.
