AlterEgo is a closed-loop, non-invasive, wearable system that allows humans to converse in high-bandwidth natural language with machines, artificial intelligence assistants, services, and other people without any voice—without opening their mouth, and without any discernible movements—simply by vocalizing internally. The wearable captures electrical signals, induced by subtle but deliberate movements of internal speech articulators when a user intentionally vocalizes internally, in likeness to speaking to one’s self. We use this to facilitate a bi-directional natural language computing system, where users receive aural output through bone-conduction earphones without obstructing a user’s physical senses. This enables a user to transmit and receive streams of information to and from a computing device or any other person without any observable action, in discretion and without invasion of the user’s privacy. AlterEgo aims to combine humans and computers—such that computing, the internet, and AI would weave into human personality as a “second self” and augment human cognition and abilities.