AlterEgo, a computer interface developed by Massachusetts Institute of Technology (MIT) researchers, can transcribe words that the user vocalises internally. The system is comprised of a wearable intelligence-augmentation (IA) device and an associated computing system, enabling humans to converse in high-bandwidth natural language with machines, artificial intelligence (AI) assistants and other people without necessarily speaking nor externally perceptible movements of the mouth. A bone-conduction earpiece is also incorporated into the device to transmit vibrations through the bones of the face to the inner ear. Information is conveyed to the user through the IA device without getting in the way of the conversation or otherwise obstructing the auditory experience of the user.

The wearable IA device can pick up neuromuscular signals in the jaw and face – the subtle movements of internal speech articulators vocalised intentionally and internally, but undetectable to the human eyes. The captured signals are then sent to the machine-learning system, which has been trained to correlate specific signals with particular wordings. In experiments, the IA device could learn different signals and words by identifying the numbers 0 to 9 and about a hundred English vocabularies, with an accurate transcription rate of up to 92%, which is close to the 95% accuracy of the voice function provided by Google and of actual human conversations.

In the future, AlterEgo aims to merge humans and computers together so that computing, the Internet and AI will weave into the human personality as a "second self" and human cognition and abilities can therefore be augmented.