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Cochlear ImplantsThe cochlea is another name for the auditory nerve. In the normal hearing process sound waves enter the ear as acoustic energy. The membranes, bones and fluid of the middle and inner ear vibrate in sympathy with the frequency and amplitude of this energy magnifying it as much as ten fold. This magnified energy is then sent to the cochlea which then sends it to the brain where it is interpreted as the sensation we call sound. If that sound is speech further interpretations associate it with concepts. If it is an environmental sound, such as a dog barking or phone ringing then the brain associates the sound with the event it represents.
When the nerves of the middle and inner ear do not respond to acoustic energy that is called nerve deafness and a cochlear implant may be recommended. The implant picks up sound by a tiny microphone which sends it to a speech processor where it is transformed into electric energy. This energy then travels across the person's skin to a receiver which sends it to the implant itself—an array of electrodes placed very close to the cochlea. In this way the damaged nerves of the middle and inner ear are bypassed altogether and sound waves, in the form of electric rather than acoustice energy, are sent directly to the cochlea or auditoy nerve which sends them to the brain. If the audirory nerve is also damaged a brain stem implant may be recommended.
People may receive an implant at any age; however, those who acquired speech prior to the onset of deafness often find it easier to understand speech than do those who were born deaf or were deafened before acquiring speech. This is most likely because for people with normal hearing the experience of normal conversation involves a great deal of interpretation. When encountering speech for the first time as an adult what one has been taught to listen for may be far more formal than what one would actually hear in a normal environment where the acoustics of a room may be less than optimal, background noise may be competing with the conversation one is trying to hear and the speaker may not be enunctiating clearly. As a result, there will be a lot of missing sounds. It is difficult to understand "Wha timisit?" in a crowded auditorium when one has been taught to listen for "What time is it?" in a sound proof box.
My own hearing went down very slowly. Up until age twelve I was not even aware that there were things I was not hearing because there was so much I could hear. It went down slowly but with noticeable increments. At about age 23—just around the time I graduated from college—I found that I could no longer use the phone. My hearing aides had allowed me to use the phone, albeit, not without having to ask people to repeat themselves from time to time or use different wording. But sometime during my senior year of college I found the hearing aides just weren't helping and that's the time I mark as the onset of profound deafness.
It wasn't a simple matter of going to the audiologist and saying "I'm deaf. I want a cochlear implant." I underwent a battery of psychological as well as physical tests to ensure I was a good candidate for a successful implantation. I scored high on all levels, scheduled the operation and you can read the whole story in Speaking for the Child
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