IF YOU have ever tried to mimic Elvis鈥檚 trademark lip curl, you will know that it makes talking feel wrong 鈥� never mind how you sound. People who have become deaf as adults may use the same sense to retain their speech.
David Ostry and Sazzad Nasir at McGill University in Montreal, Canada, asked five deaf and six hearing adults to say short words while their jaw motion was disturbed by a robotic arm. The nudge was too gentle to affect speech, with most people not realising that their jaw was being moved a couple of millimetres.
Nevertheless, after several hundred words all of the deaf people corrected for the distortion by moving their jaws back against the robot. They did the same when the experiment was repeated with their cochlear implants switched on. Only four of the six people with hearing adjusted to the robot, possibly suggesting that deaf people are more aware of their mouth movements, says Ostry (Nature Neuroscience, ).
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鈥淲hen you talk you want to get the movement right perhaps as much as you want the speech to sound correct,鈥� says Ostry.
