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Silent mandibular oscillations in vocal babbling
R P Meier1, L McGarvin, R A Zakia
1Department of Linguistics, University of Texas at Austin 78712, USA. rmeier@mail.utexas.edu
Abstract:
Early babbling has been characterized as being fundamentally a mandibular oscillation: the infant's repeated lowering and raising of its mandible yields a perceived contrast between consonants produced in a closed vocal tract configuration and vowels produced with an open tract. We wondered whether babblers produce rhythmic mandibular oscillations without phonation and, if so, whether there might be a relationship between such 'jaw wags' and early speech. We report two studies: the first is a longitudinal, observational study of 14 infants, some of whom were hearing and some Deaf. Seven infants (3 hearing, 3 Deaf, and 1 hearing-impaired) produced numerous speech-like, rhythmic jaw wags without phonation; sometimes jaw wags formed a single utterance with phonated babbling. Most jaw wags reported here were produced when these infants were ages 8-13 months. The second study, a survey of 90 parents of 4- to 10-month-old hearing infants, suggests that silent babbles may be a widespread phenomenon of early speech development.
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