Children who struggle to hear in a noisy school environment can train their brains to filter out background noise and improve their listening skills, says a new report by the University of Washington. Hard of hearing children have difficulty hearing what's going on in the classroom despite hearing aids and assistive listening devices that amplify the teacher's voice.
"It's not a fair playing field with their normal-hearing peers," said Jessica Sullivan, lead author and a University of Washington assistant professor of speech and hearing sciences. "They have the best technology, but it's not enough – they still miss things."
The report found that children with hearing loss who had a three week auditory training program showed a 50 percent increase in comprehension in noisy environments. The children demonstrated this ability when tested three months after the end of the training. Other studies have shown that similar training can help hard of hearing adults.
People with normal hearing can easily filter out background noise. For example, if a loud truck roars by, they can still understand a conversation because their brains can fill in the sounds they may have missed.
People with hearing loss are slower to take in sound, and the parts of the brain that process hearing are less able to fill in muffled information. Repeated exposure to speech that is masked by noise teaches the brain how to receive auditory information and process it more effectively.
Children and adolescents 6 to 17 years of age attended seven one hour sessions during a three week period. They listened to a several sentences that were masked by staticky background noise similar to a noisy classroom, such as: "We saw two brown bears" or "Grandmother gave Bob red beans."
As the sessions progressed, Sullivan gradually increased the number of words in the sentences, the volume of the noice, and time between hearing the sentence and identifying the words. The children had to provide 80 percent of the correct answers before advancing to the next level.
The auditory training included a cracking noise known as “interrupted” because the white noise had fleeting 5 to 95 millisecond silences. Sullivan found that this type of white noise increased comprehension more than uninterrupted white noise. Hard of hearing children in the interrupted noise group showed approximately a 50 percent increase in their ability to understand speech compared to their hearing ability at the beginning of the experiment.
“The maintenance of the improvement is a truly significant finding," Sullivan said. "It indicates that new hearing and listening strategies have been developed to detect speech despite noise."
More research will be done to see how the regimen works for others such as adults and cochlear-implant users. The study was published in the January issue of the "Journal of the Acoustical Society of America."