$225,000 Grant Supports Effort to Enhance Devices' Functionality in Noisy Settings
March 19, 2008 - Cochlear implants have restored partial hearing to thousands of people in the past decade, but recipients generally agree that the devices leave something to be desired in noisy environments.
Yi Hu of The University of Texas at Dallas is working to change that, thanks to a three-year $225,000 award from the National Institutes of Health.
Attached to the inner ear of profoundly deaf people by an array of 16 to 24 electrodes, cochlear implants work fine in a quiet environment. But inside a busy restaurant or out on a bustling urban street, without the richness of aural detail provided by thousands of cells in a healthy ear, cochlear implant recipients find that the voice of the person right next to them quickly disappears in the general racket.
"Rapid deterioration of speech understanding in noisy environments is perhaps the No. 1 complaint of cochlear implant users, and in this project we are focused on developing environment-optimized, easy-to-integrate noise-reduction methods," said Hu, a postdoctoral fellow in electrical engineering in the UT Dallas Erik Jonsson School of Engineering and Computer Science.
He's taking a two-pronged approach. On the one hand, he's evaluating how the level of compression of the audio signals that the cochlear implant sends to the brain affects the ability to hear speech in a noisy environment. Previous research suggests that the optimal level of compression in a noisy setting may be different from the optimal level in a quiet environment.
The other half of the equation involves creating algorithms that act as digital filters for specific environments. That's possible because the noise in a sports stadium and the noise in a crowded mall each have their own signature - or time-frequency characteristics, to be precise. And those characteristics can be analyzed, averaged and largely filtered out, leaving the voices of the people around you.
Hu's work may help the cochlear implant recipient of tomorrow selectively filter out sports stadium noise with one setting and restaurant noise with another, leaving the voices of people nearby coming through loud and clear.
In addition to developing the algorithms and optimizing the compression, Hu will work with approximately 10 cochlear implant recipients over the next three years, inviting them into the lab for a couple days of testing and then sending them home with the new technology.
"We will work with the participants to tune and optimize the technology in the lab," he said, "but then the real test is for them to take it home and see how it works in the real world."
Hu received his Ph.D. in electrical engineering in 2003 from UTD under the supervision of Philip Loizou, a professor of electrical engineering and director of the Cochlear Implant Lab. He has been working with Loizou ever since on noise-reduction algorithms for cochlear implants.
