INFANT COOING BABBLING LINKED TO HEARING ABILITY
Infants' vocalizations
throughout the first year follow a set of predictable steps from crying and
cooing to forming syllables and first words. However, previous research had not
addressed how the amount of vocalizations may differ between hearing and deaf
infants. Now, University of Missouri research shows that infant vocalizations
are primarily motivated by infants' ability to hear their own babbling.
Additionally, infants with profound hearing loss who received cochlear implants
to help correct their hearing soon reached the vocalization levels of their
hearing peers, putting them on track for language development.
"Hearing is a
critical aspect of infants' motivation to make early sounds," said Mary
Fagan, an assistant professor in the Department of Communication Science and
Disorders in the MU School of Health Professions. "This study shows babies
are interested in speech-like sounds and that they increase their babbling when
they can hear."
Fagan studied the
vocalizations of 27 hearing infants and 16 infants with profound hearing loss
who were candidates for cochlear implants, which are small electronic devices
embedded into the bone behind the ear that replace some functions of the damaged
inner ear. She found that infants with profound hearing loss vocalized
significantly less than hearing infants. However, when the infants with
profound hearing loss received cochlear implants, the infants' vocalizations
increased to the same levels as their hearing peers within four months of
receiving the implants.
"After the
infants received their cochlear implants, the significant difference in overall
vocalization quantity was no longer evident," Fagan said. "These
findings support the importance of early hearing screenings and early cochlear
implantation."
Fagan found that
non-speech-like sounds such as crying, laughing and raspberry sounds, were not
affected by infants' hearing ability. She says this finding highlights babies
are more interested in speech-like sounds since they increase their production
of those sounds such as babbling when they can hear.
"Babies learn so
much through sound in the first year of their lives," Fagan said. "We
know learning from others is important to infants' development, but hearing
allows infants to explore their own vocalizations and learn through their own
capacity to produce sounds."
In future research,
Fagan hopes to study whether infants explore the sounds of objects such as
musical toys to the same degree they explore vocalization.
Fagan's research,
"Frequency of vocalization before and after cochlear implantation: Dynamic
effect of auditory feedback on infant behavior," was published in the Journal
of Experimental Child Psychology.
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