Early phonetic and lexical development: a productivity approach.
Researchers frequently examine the development of the single-word lexicon in the absence of phonetic data. Yet a large body of literature demonstrates relationships between the phonetics of babble and early speech, and it is clear that production skill is essential for establishing a lexicon. This study uses longitudinal productivity criteria to establish children's phonetic skill. Twenty children were followed from age 9 to 16 months, and their level of consistency of vocal patterns was examined in relation to their lexical production, providing a relatively large-sample demonstration of phonetic/lexical relationships at the transition to language. Number of specific consonants produced consistently across the months of observation predicted referential lexical use at 16 months, whereas the transition to reference itself signaled the onset of a sharp increase in numbers of different words produced in a session. The earliest referential speakers exhibited prior consistency in the production of [p/b], which also predominated in their words. Prior use of at least two supraglottal consonants characterized the referential group. Children varied in the specific consonants they produced consistently, and these same consonants, varying according to individual child repertoire, characterized nearly all consonant-based words produced by each child in both of the final 2 months of observation. These findings are interpreted in relation to the children's contemporaneous development of representational ability and pragmatic skill.