Cochlear Implants
1. Headset 2. Cable to speed processor 3. Microphone 
      4. Implant 5. Auditory Nerve 6. Brain
1. Headset 2. Cable to speed processor 3. Microphone 4. Implant 5. Auditory Nerve 6. Brain

Have you ever wondered what it would be like to hear?

Many people take their hearing for granted. Until the early 1980's deaf and hearing-impaired people have only dreamt about the hearing world. Cochlear implants are now making those dreams come true.

Understanding how cochlear implants work is best explained by first considering how normal hearing works and what problems cause deafness.

"In normal hearing, sound waves travel along the external ear canal and cause the tympanic membrane (ear drum) to vibrate.

The three small bones of the middle ear (malleus, incus and stapes) conduct these vibrations to the cochlea," according to Donald K. Eddington, Ph.D and Michael L. Pierschalla. The cochlea is the spiral-shaped cavity of the inner ear that contains nerve endings essential for hearing.

Normal pathway of sound.
Normal pathway of sound.

Cochlear hair cells translate the acoustic energy of sound into electrical signals, which is carried to the brain by auditory nerve fibers. Damage to these hair cells results in sensory nerve hearing loss-deafness.

Cochlear implants bypass damaged hair cells by directly stimulating the auditory nerve fibers in the cochlea (inner ear.)

In the surgical procedure, an array of electrodes is implanted into the cochlea. It is attached to a small, directional microphone located in the headset (a casing resembling a hearing-aid) wrapped around the ear. This microphone receives sound that is transferred to the attached speech processor.

The brain interprets the coded signals from the speech processor-a powerful miniature computer that filters, analyzes, and digitalizes sounds into coded signals. The speech processor is the size of a portable cassette player and is worn on a belt or carried in a pocket.

The coded signals are sent to the transmitting coil where they are passed along as FM radio signals to the cochlear implant located just under the skin. Electrical energy is then delivered to the implanted electrodes, stimulating the auditory nerve fibers. Finally, sound is transmitted to the auditory system for the brain to interpret.

Over 30,000 individuals have benefited from cochlear implants, fulfilling their dreams of hearing.

Writing
Amanda Mancheski
A junior studying Agricultural Journalism with a Genetics emphasis.
Photography
UW Hospital
HTML Markup
Kurt Wagner

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