Electrodes have been implanted in the brain of Eric Ramsay, who has been “locked in” — conscious but paralysed — since a car crash eight years ago.

These have been recording pulses in areas of the brain involved in speech and plan to use the signals he generates to drive speech software.

Researchers at Boston University believe they can correctly identify the sound Mr Ramsay’s brain is imagining some 80 percent of the time.