Silent mandibular oscillations in vocal babbling.
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.
Meier
R P
RP
Department of Linguistics, University of Texas at Austin 78712, USA. rmeier@mail.utexas.edu
McGarvin
L
L
Zakia
R A
RA
Willerman
R
R
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