As early as 1975, researchers have been testing “the feasibility of designing a close-coupled, two-way communication link between man and computer using biological information from muscles of the vocal apparatus and the electrical activity of the brain during overt and covert (verbal thinking)
An interview with Chuck Jorgensen, Chief Scientist for Neuroengineering at the NASA Ames Research Center in Moffett Field, California, explains that:
Subvocal speech is silent, or sub-auditory, speech, such as when a person silently reads or talks to himself. Biological signals arise when reading or speaking to oneself with or without actual lip or facial movement. A person using the subvocal system thinks of phrases and talks to himself so quietly, it cannot be heard, but the tongue and vocal cords do receive speech signals from the
brain.… Quiet cell phones would be one commercial application; possibly communication between divers, is another. Anyone who needs to use noisy haz-mat suits or work in high-noise environments could benefit from this technology. Environments where you want privacy, such as in teleconferencing and you want to talk to someone around the table
