How deaf people can “hear” with their tongue

The expression “to have the words on the tip of your tongue” could take on a new and unexpected meaning for the 360 million people worldwide (5 per cent of the global population) who suffer from incapacitating hearing impairments. A new prototype developed by researchers at Colorado State University (CSU) enables deaf people to hear not with their ears, but with their tongue.At present, people with hearing impairments can be fitted with cochlear implants. These work by converting sounds captured by microphones into electric impulses, which are then transmitted by electrodes implanted in the cochlea to stimulate the auditory nerve (the cochlea is the internal ear and is the organ responsible for both hearing and balance). While these devices are effective, they require complicated and expensive surgery (though this can be funded by state health services). Hence the idea for this new prototype.
What we are trying to develop another form of sensory substitution
New meaning
“What we are trying to develop another form of sensory substitution,” explains John Williams, a former expert in electric propulsion systems who switched to neurosciences and led the team at CSU. The tongue is the ideal organ because it is hypersensitive. “The tongue contains thousands of nerves and the part of the brain that interprets sensations of touch from the tongue is capable of decoding complex information,” says Williams. “We’re able to discriminate between specific points that are extremely close to one another on the tongue,” adds his colleague Leslie Stone-Roy, assistant professor at CSU College of Veterinary Medicine and Biomedical Sciences. “The tongue’s acuity is similar to that of our fingertips, which we use to read Braille.”
Feels like champagne bubblesThe system, which has undergone testing, also relies on a microphone that is linked to a Bluetooth earpiece and can detect ambient sound. A software program then analyzes this background noise, extracts words from it, and translates them into electric impulses. Users place a small lollipop-shaped device comprising micro-electrodes in their mouth. On contact with the tongue, it stimulates the nerve cells. This sensation should prove popular: the researchers describe it in no uncertain terms as being similar to the fizz of champagne bubblesThe device has to be used for weeks or maybe even months before the brain is able to decode the signals easily. For example, every time the microphone hears the word “ball”, the device stimulates the same nerve pattern on the tongue. Over time the brain learns to associate this particular sensation with the relevant word, making it easier to recognize in future. Ultimately, it is based on the same concept as Braille, which blind people use to link a pattern of small raised dots and dips with words.Sounds of progressHowever, this breakthrough will not make sign language redundant: the researchers find their system is better suited to people who are not completely deaf.Williams is currently fine-tuning the map of the nerves in the tongue in order to identify the most suitable areas to stimulate. While the current prototype is heavy and cumbersome, the engineer is working on a smaller, perhaps even microscopic version that should not cost more than 2,000 dollars (1,720 euros).
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Words in the mouth: CSU device lets you hear with your tongue(Colorado State University)EDF PULSE AWARDSDiscover all the projects competiting in the category health

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