Tongue clicking is a vital part of language for some southern African groups, such as the !Kung. And it could soon help paralysed people steer their wheelchairs. The key is an in-ear device that listens out for clicks and tuts and translates the sounds into commands for a wheelchair. Mouth interfaces that interact with wheelchairs are already quite common for severely disabled people. One retainer-like device that fits within the roof of the mouth houses buttons that can be pressed with the tongue. "But everything that involves tongue movement requires putting something in the mouth," says Ravi Vaidyanathan of the University of Bristol, UK. Besides issues of hygiene, these devices make it difficult for the user to eat or speak, if they are able to, while using it.
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