An acoustic analysis of the development of CV coarticulation: a case study.

This study analyzed stop consonant-vowel productions from babbling to meaningful speech in a single female child spanning the period from age 7 months to age 40 months. A total of 7,888 utterances (3,103 [bV], 3,236 [dV], and 1,549 [gV]) were analyzed to obtain frequencies at F2 onset and F2 at vocalic center for each utterance. A linear regression line ("locus equation") was fit to the cluster of F2 coordinates per stop place category produced during each month. The slope of the regression lines provided a numerical index of vowel-induced coarticulation on consonant productions. Labial, alveolar, and velar CV productions followed distinct articulatory paths toward adult-like norms of coarticulation. Inferences about the gradual emergence of segmental independence of the consonant and vowel in the three stop place environments were made from locus equation scatterplots and mean F2 onset and F2 midvowel frequencies obtained across babbling, early words, and natural speech.