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Cochlear Implants


The cochlear implant is an electronic device that restores partial hearing to the deaf.


The ear is divided into three parts: external ear, middle ear, and inner ear.

Sound travels along the ear canal of the external ear and causes the ear drum to vibrate. The three small bones of the middle ear conduct this vibration from the ear drum to the cochlea or auditory chamber of the inner ear. Fluid waves in the cochlea, initiated by movement of the three small ear bones, stimulate the more than sixteen thousand delicate hearing cells (hair cells). Movement of these hair cells generates an electrical current in the auditory nerve. This current is transmitted through various complicated interconnections in the brain stem to that portion of the brain that recognizes these electrical stimulations as sound.

When there is disease or obstruction in the external or middle ear, a conductive hearing impairment results. This impairment may be due to a variety of problems and may be corrected by medical or surgical treatment.

When the hearing impairment is due to a problem in the inner ear, a sensorineural impairment (nerve deafness) results. In most cases of sensorineural hearing loss, the hair cells have been damaged and do not function. Although many of the auditory nerve fibers may be intact and capable of transmitting electrical impulses to the brain, without functioning hair cells the nerve fibers remain unstimulated. Sensorineural hearing loss cannot be corrected medically.


How effective is a hearing aid?

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What type of candidate would benefit from an implant?

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