Scientists turn brain signals into speech

WASHINGTON: People robbed of the ability to talk due to a stroke or another medical condition may soon have real hope of regaining a voice thanks to technology that harnesses brain activity to produce synthesised speech, researchers said.

Scientists at the University of California, San Francisco, implanted electrodes into the brains of volunteers and decoded signals in cerebral speech centres to guide a computer-simulated version of their vocal tract – lips, jaw, tongue and larynx – to generate speech through a synthesiser.

This speech was mostly intelligible, though somewhat slurred in parts, raising hope among the researchers that with some improvements a clinically viable device could be developed in the coming years for patients with speech loss.

“We were shocked when we first heard the results – we couldn’t believe our ears.

“It was incredibly exciting that a lot of the aspects of real speech were present in the output from the synthesiser,” said study co-author and UCSF doctoral student Josh Chartier.

Stroke, ailments such as cerebral palsy, amyotrophic lateral sclerosis (ALS), Parkinson’s disease and multiple sclerosis, brain injuries and cancer sometimes take away a person’s ability to speak.

Some people use devices that track eye or residual facial muscle movements to laboriously spell out words letter-by-letter, but producing text or synthesised speech this way is slow, typically no more than 10 words per minute.

Natural speech is usually 100 to 150 words per minute.