Since their introduction, cochlear implants have transformed the lives of many people across the world, allowing deaf or severely hard-of-hearing individuals to regain their sense of sound. Unfortunately, the devices also have their drawbacks; they have to be surgically implanted, aren’t suitable for all forms of hearing loss, and can cost a whopping $100,000.
But now, an alternative could well be on the horizon, as scientists from Colorado State University (CSU) have come up with a novel way to achieve the same outcome: a device that allows users to “hear” with their tongues. The system doesn’t restore hearing, but rather it converts sounds into distinct patterns of vibration that can be felt by the tongue, and thus helps the user to interpret sensations as sounds or words. Not only would this technology be significantly cheaper than cochlear implants, but it wouldn’t require surgery either.
Cochlear implants and hearing aids work in very different ways. Whereas hearing aids amplify sounds so that they can be detected, cochlear implants bypass damaged parts of the ear and directly stimulate the auditory nerve. Sounds from the environment are picked up by a microphone and then analyzed by a speech processor. This information is then converted into electrical impulses which are then sent to different regions of the auditory nerve. It takes some training, but eventually users learn to recognize different impulses as particular sounds or words.
The CSU device works in a similar way, but what happens to the sounds after they're picked up is different. A Bluetooth-enabled earpiece transmits sounds to a processor which then converts them into patterns of impulses that represent a word. Rather than stimulating the auditory nerve, these signals are then sent to a smart retainer held in the mouth. When the user presses their tongue against the mouthpiece, tiny electrodes within the device send out patterns of impulses that stimulate nerves on the tongue, which then fire and relay the signals to the brain.
“Some people suggest it feels like the sensation of having champagne bubbles or Pop Rocks on their tongue,” engineer and project leader John Williams told PopSci.
As explained in the video below, once you’ve taught your tongue and brain to work together, you’ve effectively taught your tongue to “hear.” It will take weeks, if not months, of training, but eventually the brain will learn to recognize the tingles as useful sound information.
The reason that the researchers chose to stimulate the tongue is because is houses thousands of nerves, and our brain is very good at interpreting complicated touch sensations from the tongue.
“We’re able to discriminate between fine points that are just a short distance on the tongue,” Leslie Stone-Roy told PopSci. “It’s similar in terms of your fingertips; that’s why we use fingers to read Braille. The tongue is similar in that it has high acuity.”
At the moment, the device is pretty hefty, but the researchers are hoping to eventually develop a smaller mouthpiece that’s like a retainer, which wouldn’t be visible. They also believe it shouldn’t cost more than $2,000, which is significantly cheaper than cochlear implants. There’s much more work to be done, but for now, the team is focusing on mapping the nerves on the tongue so that the researchers can select the best places to stimulate.