Study: Toddlers with cochlear implants experience slower language processing during a word recognition task
by Mark McGowan
Toddlers fitted with cochlear implants take more time, on average, to
process spoken words in their vocabulary than their normal-hearing peers,
according to a study led by a professor from NIU.
Tina Grieco-Calub, who was a post-doctoral student at the University of
Wisconsin-Madison during the time of the 2006-2008 study, said that those
time delays – on the order of milliseconds – could impact how children with
cochlear implants learn new words.
And, Grieco-Calub said, if these children are taking longer to process the
words that they know, they might miss opportunities to learn new words and
expand their vocabularies.
Published in the December 2009 issue of the Journal of Speech, Language and
Hearing Research, the research funded by a National Institutes of Health
grant gives clinicians and parents the understanding that children with
cochlear implants need more time to process auditory information.
Cochlear implants are intended only for children who have severe to profound
hearing loss or who are deaf.
“There are a number of published studies involving school-age children with
cochlear implants that look at their language outcomes – standardized
measures of spoken language performance, expressive or receptive – but they
don’t tell us how these children are processing auditory information on a
real-time basis,” Grieco-Calub said.
“This gives us insight into how children process language, particularly when
their vocabularies are starting to emerge – right in the middle of the
language explosion,” she added. “Even though their language appears to be
developing, many children do not appear to be processing information as
efficiently as children with normal hearing.”
Grieco-Calub and her co-researchers, Jenny Saffran and Ruth Litovsky, used
video cameras and special software to digitally record eye movements and
determine the length of reaction time from spoken cue to visual response.
Forty-six 2-year-old children participated, 26 of whom have cochlear
Four objects – baby, ball, doggy and shoe – were chosen for the study. “We
verified with their parents that those words were in their vocabularies,”
Children were seated in a double-walled, sound-attenuated booth. As the
researchers played recordings of questions regarding the test words – “look
at the,” “where is the” and “can you find” – children turned their eyes
toward the corresponding objects.
The toddlers were seated in infant seats or on the laps of caregivers, who
were listening to music via earphones to eliminate the possibility that they
might bias the children’s behavior during the experiment.
“On average, children with cochlear implants took longer to look at the
target objects after hearing the target label,” Grieco-Calub said. “Some did
perform similarly to their normal-hearing peers but others performed much
Researchers also discovered that adding acoustic competition – a background
noise of two-talker babble – further slowed the reaction time of both groups
of children. The researchers believe this could have implications for
children who need to comprehend language when there is considerable
Consequently, Grieco-Calub said, parents and teachers should strive to
minimize background noise and provide visual cues.
Grieco-Calub is a professor in the School of Allied Health and Communicative
Disorders, housed in the NIU College of Health and Human Sciences.