ORGANIZATION OF BABBLING - A CASE-STUDY

Speech is probably the most complex serially ordered behavior in livin g forms. However, no systematic investigation of the organization of s peech-related output when it is presumably simplest, namely during the babbling stage, has been attempted. Transcriptions of 423 babbled utt erances (1145 syllables) were obtained from one subject 7 - 12 months of age. Most results could be interpreted in terms of a basic mouth op ening-closing alternation, responsible not only for the typical vowel- consonant alternation of babbling, but also for many prominent details including within-utterance variation in vowel height (often stress-re lated) and in degree of closure for consonants. The results suggest th at a ''frame'' for babbling is provided by mandibular oscillation, per haps reflected, when operating alone, in the common alternation betwee n labial consonants and central vowels. Variation in the amplitude of this oscillation may be responsible for the within-utterance vowel hei ght and consonant manner variation and much of the perceived stress va riation. Further variation is attributed to fronting movements of the tongue, the effects of which often spread beyond single vowels and con sonants.