Scientists at NASA’s Ames Research Center are developing a way to communicate silently, using only the throat and tongue. Talking without moving the mouth is called subvocal speech; you may do it unconsciously when you read or think. Using sensors attached to the throat, Chuck Jorgensen of NASA can detect the nerve signals that fire during subvocal speech and translate them into words. So far the system recognizes only a limited vocabulary, but it works. The goal is to facilitate communication in situations where ambient noise, the need for privacy, or physical impediments make it impractical to speak out loud. Astronauts, for example, often have trouble speaking due to pressure changes in the vocal cavity and swelling of the throat. “We are looking at the direct connection from nervous system to machine, bypassing the requirement for the physical body,” says Jorgensen, who heads NASA’s Extension of the Human Senses program. “There is no visible outside movement at all; I think that’s kind of cool.” If he can perfect his subvocal speech reader, people ranging from spies to stroke victims may agree.