Now Hear This! Cochlear Implants Change Lives!

Posted by: Jason Taylor on September 1, 2010 at 2:49PM
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I bet you didn’t know you had so much stuff in there! Don’t worry, not many people do. In fact, few of us understand and appreciate what is, I think, one of the most incredible feats of our evolution as animals: hearing. Each moment of every day, your brain receives countless stimuli in the form of acoustic energy - that is to say - sounds. You can’t feel it, let alone control it, but every pin drop, every greeting and every honking horn is causing tiny hair cells in your inner ear to vibrate. Hair cells reside in the Organ of Corti (below, left), a “sensory end organ” (like the retinas in your eyes) that takes in data from the outside world and encodes them into electrical impulses your brain turns into sensation. The Organ of Corti runs along the center of the spirally helix that is your cochlea (below, right). So what does that all mean? It means that your entire ability to hear relies on the snail-shaped, fluid-filled cochlea in each ear; without it or any of its marvelous parts, you would never know that sound even existed.



Some people are born with a cochlea that is damaged or mutated beyond the ability to maintain a normal hearing level. This may be because of a mutation in its shape (because it is an astonishingly fine-tuned piece of equipment) or in the hair cells and Organ of Corti themselves. Children born with misshapen or otherwise ineffective cochleae never hear their mothers’ voices, let alone anything else, until something is done to save them from their silent world and allow them to experience one of the most essential senses of the animal kingdom – the ability to hear.

In 2003, about 79,522 children were treated for hearing disorders under the Individuals with Disabilities Education Act in the United States. By 2009 - 25,500 children in the U.S. had received cochlear implants to aid their hearing disabilities and allow them to experience the world more similarly to their hearing peers. But what is a cochlear implant?

Cochlear implants bypass the damaged or defunct parts of the middle and inner ear and get right to the good stuff, in this case the Auditory Nerve. The Auditory Nerve, also known as Cranial Nerve VIII, is the pathway of special neurons that carry sound signals to the speech and hearing centers of the brain. In a normally functioning auditory system, sound vibrations reach the cochlea where the hair cells inside vibrate according to the frequency of the sound. These vibrations are translated by the hair cells into electrical impulses, which then head to the brain via the Auditory Nerve. Okay. So where do cochlear implants come in? Well a cochlear implant, as you can see below, acts like the hair cells and translates sound vibrations into electrical impulses. It then feeds these impulses directly into the Auditory Nerve using a series of electrodes implanted in the cochlea. If it sounds simple, read it again. This is amazing stuff!

It’s amazing because it means that even without, for all intents and purposes, the parts of the body that cause hearing, people are still able to interpret sounds in almost exactly the same way as your average Joe. Still not impressed? Think of it this way: it’s taken evolution millions and millions of years to go from sludge…to the amazing and intricate little cochlea. What cochlear implants do is essentially use a tiny machine to do the same job it took nature millions of years to figure out!

If, at the end of my auditory adoration you’re still not impressed, at least get excited for little Jonathan. In this video he’s hearing his mother’s voice for the very first time!