Inhibiting infants’ tongue movements impedes their
ability to distinguish between speech sounds,
researchers with the University of British Columbia
have found. The study is the first to discover a
direct link between infants’ oral-motor movements
and auditory speech perception.
In the study, published October 12 in the
Proceedings of the National Academy of Sciences,
teething toys were placed in the mouths of
six-month-old English-learning babies while they
listened to speech sounds—two different Hindi “d”
sounds that infants at this age can readily
distinguish. When the teethers restricted movements
of the tip of the tongue, the infants were unable to
distinguish between the two “d” sounds. But when
their tongues were free to move, the babies were
able to make the distinction.
Lead author Alison Bruderer, a postdoctoral fellow
in the School of Audiology and Speech Sciences at
UBC, said the findings call into question previous
assumptions about speech and language development.
“Until now, research in speech perception
development and language acquisition has primarily
used the auditory experience as the driving factor,”
she said. “Researchers should actually be looking at
babies’ oral-motor movements as well.”
The study does not mean parents should take their
babies’ soothers and teething toys away, but it does
raise questions about how much time infants need
with ‘free’ tongue movement for speech perception to
develop normally. It also has implications for
speech perception in infants with motor impairments
of the mouth, such as cleft palate, tongue-tie or
paralysis.
“This study indicates that the freedom to make small
gestures with their tongue and other articulators
when they listen to speech may be an important
factor in babies’ perception of the sounds,” said
senior author Janet Werker, professor in the UBC
Department of Psychology.
For more information
Sensorimotor influences on speech perception in
infancy
link...
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