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Understanding Cochlear Implants

If you're severely hard of hearing or profoundly deaf, a cochlear implant may help you to regain a sense of sound. A cochlear implant isn't a hearing aid, which amplifies sound. A cochlear implant is a small, surgically implanted device that works by delivering impulses directly to the auditory nerve, which carries the signals to the brain.

Although a cochlear implant doesn't restore normal hearing, the device can give you a useful representation of sounds. Most people are able to understand speech in person or over the phone better than they did with a hearing aid, as well as perceive sounds in the environment, including telephones, doorbells, and alarms. Many people are also able to understand speech in noisy environments better than they did with hearing aids, and are even able to enjoy music again. 

How does a cochlear implant work?

Cochlear implants are designed for children and adults with sensorineural hearing loss. This type of hearing loss typically involves damage to tiny hair cells in the cochlea. As a result, sound can't reach the auditory nerve, which usually receives information from hair cells. A cochlear implant bypasses the damaged hair cells to stimulate the auditory nerve directly.

What happens, exactly? If you get a cochlear implant, it will consist of internal parts implanted under your skin, as well as external parts that you wear on your body, like a hearing aid. The external part with attached head coil (audio or speech processor) is slightly larger than a standard behind-the ear hearing aid. They work together to create a sensation of sound.

First, a surgeon implants a receiver under your skin behind your ear, through a small incision. The receiver is connected to electrodes, which are surgically inserted into the cochlea. The surgery takes one to two hours to perform and is typically an outpatient procedure.

One to two weeks after surgery, you will be fitted with three external parts: a speech processor, a battery pack, and a transmitter. You wear the microphone, which resembles a hearing aid, behind your ear. The audio processor may be housed with the microphone and worn completely at the ear, or it may be worn elsewhere on the body, depending on the user's activity level, age, or lifestyle. Cochlear implant audio processors offer multiple program options, telephone connection options, and the ability to connect to assistive listening devices and other listening devices, like an iPod. Some offer rechargeable batteries to lower operating costs. 

When there are sounds in your environment, the microphone and processor pick them up and change them into electrical impulses. Then the transmitter sends these coded signals to the receiver under your skin. Next, the receiver delivers the signals to the electrodes inserted into the cochlea. These electrodes stimulate the auditory nerve, which carries the signals to the brain, where they are recognized as sound.