Software May Improve Utility of Implants for Deaf

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Twenty years ago, the FDA approved the first devices to help the deaf understand speech through cochlear implants. Now Duke University researchers are using software to make the implants more suitable for hearing music.


The business news starts with the way some people hear music like this.

(Soundbite of music)

INSKEEP: People who are deaf can hear sounds like this using devices called cochlear implants, but for them listening to music can be frustrating. Those implants use tiny electrodes to transmit sound signals to nerves in the inner ear, but existing models can make a sweet melody sound like a catfight. Now implant companies and academic researchers are trying to change that, as NPR's David Malakoff reports.


Public radio fans can probably identify this piece of music.

(Soundbite of "Talk of the Nation" theme)

MALAKOFF: It's the theme from NPR's "Talk of the Nation." But what if you turned on your radio and heard this?

(Soundbite of altered "Talk of the Nation" theme)

MALAKOFF: Believe it or not, it's the same song, as it might be heard by a person with a cochlear implant. More than 100,000 people now have them, and the implants have enabled many of them to hear a child's cry or a cat's meow for the first time. To be clear, researchers say it's impossible to exactly recreate what a person with an implant hears. What you heard is a best guess computer simulation. It was created by scientists at Duke University who are studying ways to improve implants. Leslie Collins is an electrical engineer who leads the project. She says the problem is that current implants can't transmit nearly as much information as a normal ear.

Ms. LESLIE COLLINS (Electrical Engineer): The basic engineering challenge here is in a normal ear, you've got about 30,000 nerve fibers that are transmitting the information to your brain so that you can basically understand and appreciate what's going on in your environment. Probably the best you can do with a cochlear implant is instead of having 30,000 channels or information sources available to you, you've got 24. So you're going from 30,000 to 24.

MALAKOFF: Thanks to some clever engineering, those 24 channels have turned out to be good enough to accurately transmit speech in quiet environments. But some people aren't very happy with what they hear when it comes to music, in particular those who became deaf as adults and have fond memories of a favorite song. Chris van den Honert is vice president for research at Cochlear Americas in Colorado. It's a leading implant maker.

Mr. CHRIS VAN DEN HONERT (Cochlear Americas): Since we now are able to represent speech reasonably well, the expectations are rising amongst our recipients and one of the things we'd like to be able to do is a better job of representing music and musical pitch. And there's a long way to go before we can restore the kind of musical experience that a normal hearing listener would enjoy.

MALAKOFF: At Duke, Leslie Collins is hoping to make that long road to a music-friendly implant a little shorter. In her lab, researchers are working on new ways of mathematically processing the sound that an implant picks up with its microphone. Josh Stohl is one of the doctoral students on the team. He works on computer programs that can tweak the timing and placement of the sound pulses that are sent to the electrodes.

Mr. JOSH STOHL (Doctoral Student): So we're going to listen to the "Talk of the Nation" theme in its original form, as you and I would hear it.

(Soundbite of "Talk of the Nation" theme)

Mr. STOHL: Now we're going to hear it as a cochlear implant patient would hear it.

(Soundbite of altered "Talk of the Nation" theme)

Mr. STOHL: And here is one of the algorithms that we're currently working on, so you'll notice an obvious improvement.

(Soundbite of altered "Talk of the Nation" theme)

MALAKOFF: The Duke researchers say that these kinds of music-processing techniques look promising in tests, but they caution that major advances are probably years away. Still, Josh Stohl says he's got a very personal stake in making progress.

Mr. STOHL: I love music, it's a big part of my life, and probably the most heartbreaking thing about coming here is hearing music through these acoustic models. That's a lot of the motivation for me to be here, is how awful it does sound right now, or how much room for improvement there is.

MALAKOFF: Implant companies are watching work like this closely. Partly that's because new sound-processing programs could be used to upgrade or fine-tune implants that their customers already have. It would be sort of like reprogramming a computer instead of replacing it. And that's important because implants can run $25,000 each or more. David Malakoff, NPR News.

(Soundbite of altered "Talk of the Nation" theme)

INSKEEP: That's our regular Monday report on business and technology.

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