Steering a wheelchair with your tongue sounds impressive enough. Doing so with your mouth closed and gadget-free is the feat allowed by a tongue-tracking earpiece due on sale later this year.

Typically, quadriplegics must suck or blow into a straw to steer a wheelchair or move a computer cursor. That can be unhygienic and irritating for the user, says Ravi Vaidyanathan, an engineer at the University of Southampton, UK.

Instead, he and Lalit Gupta of Southern Illinois University Carbondale have created a device that identifies a range of different tongue movements with 97 per cent accuracy, using a microphone that sits inside the ear. The company Think-a-Move of Cleveland, Ohio, says it will launch a wheelchair steered by the device by the end of 2007.

The key elements are a plug that seals the ear from outside noise and a microphone that points inside the ear canal. When the wearer ...