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By Technology Review
July 14, 2014

A San Francisco neurosurgeon is working toward building a wireless brain-machine interface.

Credit: Bradley Greger

Although his findings are preliminary, University of California, San Francisco neurosurgeon Edward Chang says he is working toward building a wireless brain-machine interface that could translate brain signals directly into audible speech using a voice synthesizer.
Chang has been conducting speech experiments in connection with brain surgeries he performs on patients with epilepsy. A sheet of electrodes placed under the patients' skulls records electrical activity from the surface of the brain. Patients wear a device called an electrocorticography array for several days to enable doctors to locate the exact source of seizures.
In a paper published in the journal Nature last year, Chang and his colleagues described how they used the electrode array to map patterns of electrical activity in an area of the brain called the ventral sensory motor cortex as subjects pronounced sounds like "bah," "dee," and "goo."
The aim of the technology is to record the electrical activity in the motor cortex that causes speech-related movements of the lips, tongue, and vocal cords. By mathematically analyzing these patterns, Chang says his team showed that "many key phonetic features" can be detected.

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