What is a cochlear implant?

Ok, some context may be required here as to why I now have a computer in my head, and which is due to be booted up on 13th September.

If you’re reading this, the chances are you know something about cochlear implants, but if you don’t, here’s a reasonably succinct, 100-word explanation:

A cochlear implant consists of two parts: an internal part that is surgically inserted and wired directly into my middle ear,

and an external processor that looks very much like a hearing aid.

A conventional hearing aid works by essentially blasting sound into your ear and can work if you have enough of what is called ‘residual’ hearing. But if you don’t have enough residual hearing, or you are totally or almost totally deaf, a cochlear implant can work by sending sound information directly into your middle ear (the cochlea).  The processor takes in sound, digitises it, and sends to my cochlea in the form of electrical pulses. Because this sound sensation is totally different, it takes a bit of time to understand the sound that comes through.

If that explanation doesn’t tell you enough, here is a 300-word explanation:

A cochlear implant is a device in two parts: The first part is the internal implant that is surgically inserted into my inner ear and part of my skull. The second, external part is the processor, which looks a bit like a hearing aid. The body of the implant contains the electronics, a magnet and a long wire called an electrode. To insert it, the surgeon creates carves out a well for the body and magnet part to sit in so that it’s more or less flush with my skull. A hole is drilled into the bone behind my ear all the way into the place where my cochlea and auditory nerve live. Theses are the important parts of the hearing system that interpret sound coming in the ear. The reason my cochlea doesn’t really work properly is that the little hairs that help interpret sound and send signals to my brain are almost completely worn away or damaged. If the hairs are only partially damaged (as they had been in my case for a long time), hearing aids help by essentially amplifying sound to the point where the damaged hairs can send enough signals to the brain to interpret as sound, but if the hairs are too damaged then they can’t do much. A cochlear implant gets around this problem by essentially by-passing the normal auditory system. The external processor takes in sound, digitises it, and sends it down a round thing that sticks to my head called a coil, which in turn is kept in place on my head by the magnet in the internal implant. The implant receives this information and sends it down to the electrode as electrical pulses. The electrode contains 22 channels through which these pulses are distributed at a rate of thousands of times a second and which the brain eventually learns to interpret as sound.

So there you go.

As you can probably appreciate, the reason it’s such a big deal is because of the surgery involved, which also makes it quite an expensive procedure.

However, as prosthetics go, it’s been proven that cochlear implants today offer a bigger improvement to an implantee’s quality of life than just about any other prosthetic device, such as a hip replacement or a mechanical arm.

Over 120,000 people worldwide now have cochlear implants, which makes it one of the most widely available such prosthetics.

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