title: Silent mandibular oscillations in vocal babbling.
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.
authors.affiliation: Department of Linguistics, University of Texas at Austin 78712, USA. rmeier@mail.utexas.edu
authors.forename: R P
authors.initials: RP
authors.lastname: Meier
authors.forename: L
authors.initials: L
authors.lastname: McGarvin
authors.forename: R A
authors.initials: RA
authors.lastname: Zakia
authors.forename: R
authors.initials: R
authors.lastname: Willerman
mesh_terms: D002663:Child Language; D005260:Female; D006801:Humans; D007223:Infant; D007804:Language Development; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010507:Periodicity; D010699:Phonation; D013060:Speech; D014743:Videotape Recording