"We were beside ourselves with excitement when it started working," said Professor Bradley Greger, a bioengineer at Utah University who led the team of researchers.
"It was just one of the moments when everything came together.
"We have been able to decode spoken words using only signals from the brain with a device that has promise for long-term use in paralysed patients who cannot now speak.
"I would call it brain reading and we hope that in two or three years it will be available for use for paralysed patients."
The experimental breakthrough came when the team attached two button sized grids of 16 tiny electrodes to the speech centres of the brain of an epileptic patient. The sensors were attached to the surface of the brain The patient had had part of his skull removed for another operation to treat his condition.
Using the electrodes, the scientists recorded brain signals in a computer as the patient repeatedly read each of 10 words that might be useful to a paralysed person: yes, no, hot, cold, hungry, thirsty, hello, goodbye, more and less.