"When the voices come from the same place and when we add more competing voices, the task gets more difficult," says Litovsky, who has tested children as young as 4. But, the researcher has also found that each child's ability to separate the different speakers varies, most likely due to individual rates of auditory and cognitive development. "Adults are generally much better at this task than children," she adds, because many aspects of hearing continue to develop into the teenage years.
By varying the test, Litovsky has also found that children have more difficulty separating competing sounds that produce a more audible reverberation, or echo. Binaural hearing generally allows humans to quiet these echoes, but Litovsky says the acoustics of a room can greatly affect this ability.
"The results from these tests lead to interesting questions about the acoustical architecture of classrooms," she says.
Litovsky will present more of these findings Thursday, June 6, at the annual Acoustical Society of America conference in Pittsburgh.
In the future, Litovsky plans to work with children who are born deaf and who receive cochlear implants to restore hearing. Through her work at the Waisman Center, Litovsky plans to use her test to assess how children with developmental disabilities, such as autism, fragile-X and Down syndrome, hear in noisy environments. "To date, almost nothing is known about hearing abilities in children with disabilities," she says. "In order to be able to help these children function in realistic environments, we must understand how they hear."
The Wisconsin Alumni Resea
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Contact: Ruth Litovsky
litovsky@waisman.wisc.edu
608-262-5045
University of Wisconsin-Madison
23-May-2002