[IVY]

SAW THIS.. thought a roach would be i nterested..
first in my health series

Tue Jul 26, 8:00 PM ET

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Sometimes called a "bionic ear," the cochlear implant offers the hope of regaining or restoring the ability to sense sound for some people who have experienced significant hearing loss. Although they're not miracle devices, cochlear implants help some children and adults, whether they're born deaf or whether hearing loss occurs later in life, experience talking on the phone, listening to music, and hearing the voices of their friends and loved ones - things a person with normal hearing often takes for granted.

What Is a Cochlear Implant?
A cochlear (pronounced: ko-klee-er) implant is a surgically implanted device that helps overcome problems in the inner ear, or cochlea (pronounced: ko-klee-uh). The cochlea is a snail-shaped bone located in the area of the ear where nerves are contained. Its function is to gather electrical signals from sound vibrations and transmit them to your auditory nerve (or hearing nerve). The hearing nerve then sends these signals to your brain, where they're translated into sounds you recognize.

If important parts of the cochlea aren't working properly and the hearing nerve isn't being stimulated, there's no way for the electrical signals to get to your brain. Therefore, hearing doesn't occur. (Sometimes referred to as nerve deafness, this is called sensorineural hearing loss, pronounced: sen-so-ree-nyur-ul.) By completely bypassing the damaged part of the cochlea, the cochlear implant uses its own electrical signals to stimulate the auditory nerve, allowing the person to hear.

How Does Normal Hearing Occur?
The ear is made up of three parts, and sound for a person who has normal hearing passes through all three on the way to the brain. The outer ear is made up of the outer, visible part of your ear and the ear canal. When a person is exposed to a sound, the outer ear captures the sound vibration and sends it through the ear canal to the middle ear, which consists of the eardrum and three tiny bones. The sound vibration then causes motion in the three tiny bones, which makes the fluid in the cochlea move. The motion of the fluid stimulates the hair cells, which are thousands of tiny hearing receptors inside the cochlea. The hair cells bend back and forth and send electrical signals to the hearing nerve, and the hearing nerve then carries these signals to the brain, where they're interpreted.

Through aging, heredity, disease, infection, or repeated or severe exposure to loud noise, hair cells can be damaged or destroyed. If the hair cells don't work, the hearing nerve can't be stimulated and therefore can't send information to the brain. Thus, the person is unable to hear.

Hearing loss can be mild, moderate, or severe, depending on the number of hair cells that are defective, damaged, or destroyed. People with mild or moderate hearing loss may find that hearing aids, which simply make sounds louder, help. Those with profound or severe hearing loss might even have trouble understanding loud sounds. A hearing aid won't help in these cases, and a doctor might recommend a cochlear implant.

What Does a Cochlear Implant Do?
The cochlear implant artificially stimulates the inner ear area with electrical signals, sends those signals to the hearing nerve, and allows the user to hear. Although sound quality is sometimes described as "mechanical" and not completely like that experienced by a person with normal hearing, the cochlear implant provides users with the ability to sense sound that they couldn't hear otherwise.

The actual cochlear implant consists of an implant package, which is secured inside the skull, and a sound and speech processor, which is worn externally (outside the body). Several components of the cochlear implant work together to receive sound, transfer it to the hearing nerve, and send it to the brain.

The implant package is made up of:

* a receiver-stimulator that contains all of the electronic circuits that control the flow of electrical pulses into the ear
* an antenna that receives the signals from the external sound and speech processor
* a magnet that holds the external sound and speech processor in place
* two wires containing electrodes that are inserted into the cochlea (the number of electrodes can vary depending on the cochlear implant model type used). The electrodes act much like normal functioning hair cells and provide electrical charges to stimulate the hearing nerve.

The sound and speech processor is a minicomputer that processes sound into digital information, and then sends that information to the implant package in the form of electrical signals. The sound and speech processor is worn externally and looks a lot like a normal hearing aid. Depending on the type of sound and speech processor used, it can either be worn as a headset behind the ear or in a belt, harness, or pocket.