The nature and origins of ambient language influence on infant vocal production and early words.

Phonological structure may be seen as emerging in ontogeny from the combined effects of performance constraints rooted in the neuromotor and perceptual systems, individual lexical development and the influence of the particular ambient language. We review here the nature and origins of the earliest ambient language influences. Global effects within the first year of life include both (1) loss of early appearing phonetic gestures not supported by the ambient language and (2) positive effects, reflecting infant attention to prosody and to cues available in the visual as well as the auditory modality. In the course of early lexical development more specific effects become manifest as individual children pursue less common phonetic paths to which the ambient language provides 'sufficient exposure'.