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ShareJanuary 1, 2005 — In a new study, 34 normal-hearing and 18 cochlear-implant subjects were tested on three speech-perception tasks known to be notoriously difficult for cochlear-implant users: speech recognition with a competing voice, speaker recognition and Mandarin-tone recognition. The researchers tested the AM and FM from a number of frequency bands in speech sounds and tested the relative contributions to speech recognition in acoustic and electric hearing.
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IRVING, Calif.--About 30 million Americans have some form of hearing loss. Many complain about hearing aids, saying they produce poor sound quality, making conversations difficult and frustrating. Now, hearing scientists are fine tuning devices to help dramatically improve what patients hear.
Imagine a world of silence. Jackie Harding knows that world.
"I'm totally deaf," she says. A cochlear implant helped Harding hear, but not much. "I would say most of the time it does not sound like music as I remember it."
Now audiologists are adding dimension to the flat sound quality in cochlear implants.
Hearing scientist Fan-Gang Zeng, of University of California, Irvine, says, "The research we're conducting will have significant impact on quality of life for cochlear implant users."
Current cochlear implants don't separate one instrument or voice from another, and music that should sound normal sounds muffled. So researchers added the FM signal you use to tune in your favorite radio station. FM, or frequency modulation, enhances voice and music recognition.
Implants now capture only the bulk features of sound -- the AM information, or amplitude. Researchers are finding new ways to capture finer sound detail -- the FM information.
Harding is using this new technology and says, "I can differentiate between the lower tones and the higher tones better than I did." Giving more dimension to sound again.
This new technology should be available to patients within the next two years and can be applied to new and existing hearing aids and cochlear implants.
We can't see them, but radio waves are all around us. Like visible light, they are a part of the electromagnetic spectrum, only with much longer wavelengths. Radio waves can be as long as a football field, or as short as a football. This range of sizes makes them ideal for sending information, because different frequencies can be assigned to specific devices to avoid overlap.
Radio works in much the same way as a telephone: sound waves are converted into an electrical current. But instead of traveling along a wire, the encoded sound data hitches a ride on a radio wave. It does this by changing either the wave's height -- also known as its amplitude -- or its frequency, which is the number of times the wave vibrates per second.
Think of the a regular radio wave as a blank sheet of white paper, and the radio wave with information on it as the ink that forms the printed words. The ink causes tiny variations in the background of the paper, and this is what the eye sees when it "reads". Mixing in a data stream of electrons causes the height or frequency of the wave to change slightly. These changes are detected by the receiver, which then decodes the information.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.
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