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March 21, 2007

Hybrid Hearing

From: - Chicago,IL,USA - Mar 21, 2007

March 21, 2007 - Twenty-eight million Americans are hard of hearing. Many have trouble hearing higher frequencies. Unfortunately, hearing aids don't always help, and devices like cochlear implants have been reserved for extreme cases ... Until now! Cochlear implants are typically a last resort because they can destroy any hearing patients do have. The cochlear implant procedure involves inserting electronics into the inner ear through a hole in the skull to replace a patient's entire range of hearing. But the procedure usually eliminates any natural hearing abilities. Until now, people couldn't get them if they had too much hearing left to benefit.

OLDER COCHLEAR IMPLANTS: Conventional cochlear implants are electronic hearing devices consisting of two main components. First, the patient wears a microphone, sound processor and transmitter system around the ear. The other component is an implanted receiver and electrode system. It receives converted sound signals from the external system and sends electrical currents to the inner ear.

People wearing conventional cochlear implants often have trouble hearing in the presence of competing speech, like at a cocktail party or restaurant, because the implant can eliminate a patient's range of hearing. People wearing conventional implants also report problems following and enjoying music. A person with a cochlear implant requires a larger separation between adjacent pitches before being able to recognize a second tone is different from the preceding one. To follow music, listeners must recognize melodies made of sequential pitch patterns. This requires a listener to perceive the direction and magnitude of pitch changes. Most people with conventional implants can't do this.

THE HYBRID IMPLANT: A new, hybrid version of the cochlear implant only adds high frequencies, so patients can hear distinct sounds -- like consonants. The words "sat" and "fat" can both sound like "ahhh." The hybrid implant allows patients to differentiate between "S" and "F." The hybrid implant uses a thinner, shorter bundle of electronics. The electrode is positioned at the opening of the cochlea, stimulating the auditory nerve where high-frequency sounds enter the ear. Patients experience less tissue trauma because surgeons don't need to probe as deeply into the cochlea. The cochlear implant is being tested in clinical trials. Since 1999, about 80 patients have received the hybrid device. Here are some of the preliminary results:

* About 96 percent of patients have retained hearing

* After at least one year with the implant, patients understand more than twice as many words on standard hearing tests on average

* Patients follow conversations even in the presence of competing speech because the hybrid implant preserves low frequency hearing, which contributes to analytic abilities of the cochlea

* Patients are able to follow and appreciate music. Hybrid implant users can differentiate between pitch changes because they retain their natural ability to perceive sounds of different frequencies

* If the hybrid implant gets FDA approval, an estimated 50,000 people could benefit from it -- twice the number of people who have a traditional cochlear implant.


* UCSF Douglas Grant Cochlear Implant Center

* San Francisco, CA 94143


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