Tested Explains: How the Bionic Ear Works

By Matthew Braga

How high-tech cochlear implants and hearing aids give us a glimpse into the potential and perils of a bionics-enhanced future.

They call it the bionic ear – an implant in the cochlea that restores the sensation of sound to those who have lost their hearing, or those who could never hear at all. There's certainly a cyberpunk ring to the term, like an upgrade for the ear. The device augments human ability by introducing (or re-introducing) functionality where there was none before.

And realistically speaking, while the notion of do-it-yourself biohacking may still be a ways off, it's tempting to think of the bionic ear as a present day glimpse into the future of human augmentation. A recent, fascinating article in the Wall Street Journal teased such a future, where brain implants and neuroprosthetics "will graduate from being strictly repair-oriented to enhancing the performance of healthy or "normal" people" – calling out the cochlear implant by name.

Photo credit: Getty Images

"What would you give for a retinal chip that let you see in the dark or for a next-generation cochlear implant that let you hear any conversation in a noisy restaurant, no matter how loud?" co-authors Gary Marcus and Christof Koch asked. It's a good question. And who wouldn't want that? But Marcus and Koch's "next-generation" caveat is key. Present day cochlear implants are amazing devices, but they're not designed to heighten an existing ability to hear – only approximate what has been lost.

Cochlear implants have been used since the late 1970s to restore the sensation of hearing to those born without, or who have lost their ability to hear in later years. An oft-cited figure is that more than 350,000 people have had the operation worldwide. The implant works by bypassing damaged or missing hair cells that typically transmit sound vibrations to the auditory nerves, and uses a bundle of electrodes to stimulate those nerves directly instead.

The electrodes run to a receiver implanted beneath the skin, and connect to an external system outside of the body via magnet – typically a microphone and speech processor that turns sound into signals that the brain can understand. (Some cochlear implants actually allow the user to plug an MP3 player or smartphone's audio output directly into their processor, like jacking a digital audio source straight into your brain. How cool is that?)

But the result isn't exactly hearing – at least, not as most people know it.

The British Columbia Adult Cochlear Implant Program describes the sound as being "anything from robotic or cartoonish speech" to just plain noise, but which the brain, with practice, learns to interpret over time. Gary Housley, a professor of neuroscience at the University of South Wales, is quoted in a recent study as saying that "people with cochlear implants do well with understanding speech, but their perception of pitch can be poor, so they often miss out on the joy of music."

Yet, the fact that we can even do this – and have been doing it for decades – is amazing.

For people that still have some natural hearing, however, a cochlear implant can actually destroy that ability for good – along with all the other potential risks that come with operating near major nerves, of course. Only adults with "moderate to severe/profound sensorineural hearing loss" in both 6ears qualify for a cochlear implant, according to the U.S. Food and Drug Administration.

The latest generation of hearing aids are the closest we have to bionics that are safe and accessible for anyone to use.

In March, however, the FDA approved what it calls a hybrid approach – a process where where those who still have some degree of low-frequency natural hearing ability, can use a cochlear implant in conjunction with a conventional hearing aid too. But it's still not the sort of procedure that just anyone can get.

If anything, the latest generation of hearing aids are the closest we have to bionics that are safe and accessible for anyone to use. The New York Time's Farhad Manjoo recently found that tech-savvy, smartphone-connected hearing aids can not only amplify sound, but amplify sound from specific locations and frequencies. It's not really bionics in the William Gibson, science-fiction, permanent augmentation sense, but unlike the cochlear implant process, also won't destroy your existing ability to hear.

Image credit: NYT

There is, of course, more pressing work to be done on cochlear implants for those who actually need them before we can move on to augmenting the natural hearing of those who don't. The fidelity could certainly be better, allowing for a wider range and accuracy of perceived sound. And there is still work to be done done on embedding the entire implant – microphone, processor, electrodes and all – beneath the skin.

But a bionic ear for all who want it? Considering what cochlear implants can already do, it's tantalizing to think what future generations of the technology could achieve.