Baby Talk
Do You Hear What I Hear?
Predictably, little Evelyn Tabor’s first word was “mama”
and making her mother Dawn Brooks proud. Evelyn was about six months
old. Since then, her vocabulary has expanded to include many of
the words a budding one-year-old might be expected to know: dada,
baby, bird, hi, Elmo.
Her proud father, Brian Tabor, thinks she also says “owl,”
since a small stuffed one is her favorite toy; he is sure she hoots
like one.
Parents eagerly await and then closely monitor their baby’s
first words. It is part of the parental process, just as applauding
a baby’s first steps is one of the many ways toddlers are
encouraged to continue the normal development process. However,
one rite of passage – the utterance of that first recognizable
word – may be delayed for the parents of infants with profound
hearing loss.
That’s where Evelyn and children like her play a role.
Otolaryngologists at the Infant Language Lab at the James Whitcomb
Riley Hospital for Children are studying language development in
normal hearing infants and toddlers. They hope to create a yardstick
language for profoundly deaf toddlers who have received cochlear
implants to allow them to understand the audible world around them.
Evelyn, a normal hearing baby, is one of the volunteers.
Little is known about babies’ talk, and just as little is
known about how babies perceive and process words and sounds from
adults and the world around them. What do normal hearing babies
actually comprehend? Can a child with a cochlear implant discriminate
sound in the same manner as a normal hearing infant? How do infants
learn to process what they hear in relation to what they see?
With answers to these questions, otolaryngology researchers at
the Indiana University School of Medicine can track the progress
of infants who use cochlear implants and provide speech therapists
a means to assess the progress of individual infants and their language
perception.
Going Ga-Ga
“Working with infants and toddlers presents unique challenges,”
says Derek M. Houston, PhD, Infant Language Lab director and assistant
professor of otolaryngology-head and neck surgery. “Progress
has been made in developing techniques to evaluate language perception
in children over the age of two, but measuring these skills in infants
who cannot follow instructions requires more innovative testing.”
Dr. Houston and his colleague Tonya R. Bergeson, PhD, assistant
professor of otolaryngology and co-director of the Infant Language
Lab, are developing new techniques for evaluating language perception
in an age group where “goo-ing” and “ga-ing”
are intense communication.
“Since this was the first lab in the world to use behavioral
methodologies to research speech and language development in hearing-impaired
infants with cochlear implants, we have paved the way for much of
the ongoing research,” says Dr. Bergeson. “We are constantly
striving to improve our methods and are in the process of equipping
our laboratory with instruments capable of following the eye movements
of the children.”
By recording how the babies respond to different stimuli, researchers
are able to evaluate how they differentiate and respond to sounds,
and how they learn language. Much of the strength of the response
is based on when or how long the child looks at a particular object.
The testing appears simple; a parent and child sit in a small,
dark room facing a large-screen television set. Hidden above the
TV is a video camera that records the movements and attention span
of the youngsters involved in the studies.
For example, in one of the studies, 5- to 13-month-old infants
see two images of the same woman, each mouthing a different word.
The woman on the left says “judge” while the one on
the right says “back.” After the infants have seen/heard
each woman “speak,” the researchers play only one of
the words. What researchers want to know is if the infant will match
the audible word with the correct lip movement. The answer is in
the baby’s eyes.
In another test, the length of time an infant focuses on a red
and white checkerboard pattern while either hearing various words
or hearing no sounds tells researchers that normal-hearing infants
are interested in speech sounds and can discriminate between them.
The same test administered to young children with cochlear implants
indicated they typically show the same discrimination in speech
after only one month of cochlear implant use.
Using varying images, sounds and stimuli, the researchers hope
to gain a deeper understanding of how language is learned and why
children who hear from birth respond differently to noises and speech
than children who were born with severe hearing impairments.
“When a normal hearing infant hears a sharp, sudden noise,
the baby looks in the direction the sound came from,” says
Dr. Houston. “Children born deaf who receive cochlear implants
do not respond to sound in the same way – the same sudden
noise may not produce a response of any kind. We want to understand
issues like this, as well as how infants learn speech.”
Talk the Talk
How much influence parents have on infant speech development also
interests the researchers at the Infant Language Lab.
“In one of our projects, we are trying to determine why mothers
instinctively use baby talk with infants,” Dr. Bergeson says.
“Interestingly, we are finding that mothers of children with
cochlear implants adjust their pattern of talking to the hearing
age of the child.” The hearing age is determined by how long
the child has had a cochlear implant, so a 20-month-old who received
an implant 12 months prior would have the hearing age of a one-year-old.
Evelyn is now an honorary member of the research team. She even
has proof – an IU School of Medicine “diploma”
designating that she has an “Infant Scientist Degree”
for her outstanding contribution to language development research.
Her diploma is framed and hangs proudly next to her mother’s
IU doctoral degree in chemistry.
“I was initially intrigued with the idea of Evelyn getting
a scientist diploma from IU, and thought her mother would be amused
too,” says her father. “When I found out more about
the research, I liked the idea of Evelyn making a contribution.
We are interested in exposing her to things, and this seemed like
a good activity. Plus, she got a really nice sippy cup – something
every infant scientist should have.”
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