Imagine the ability to talk without speaking and hear without sound. What if you could take notes, make comments, compose emails, or write a novel electronically without any of the usual peripherals? A silent communications system based on subvocalization — internal verbalization without audible or visual signals — could let you perform many everyday tasks quite quietly. Ramping up to the ability to communicate in extremely noisy or enforced quiet settings adds significant additional potential. If such a system could replace missing or severely damaged human organs or other structures, assistive technology for communication in the form silent speech becomes a powerful enabler.

Researchers at MIT Media Lab are working on two-way subvocalization technology called Project AlterEgo. Two components include a wearable headset and a machine-learning system to match internal verbalizations with specific words and phrases. The headset has two functions: neuromuscular signal detection and bone-conduction transmission. Sensitive electrodes pick up faint signals in the jaw that represent speech; these are similar to the minute movements many people may make when repeating complex directions or reading difficult passages. Bone-conduction headphones transmit vibrations via facial bones directly to the inner ear, skipping the need for audible sound. Artificial intelligence in the form of machine learning ties the two communications components together. In one experiment, students reported opponent’s chess moves and received suggested responses from a computer – all without sound. The magic sauce in the system was the neural network that matched neuromuscular signals with words.

Building such systems takes time. The MIT team described their work in a paper presented at the  Association for Computing Machinery’s ACM Intelligent User Interface conference in Japan. Initial applications could include settings such as active airfields where ground personnel need to communicate despite tremendous noise levels. The technology could also be helpful to special operations, military, and law enforcement personnel who at times need to communicate while maintaining strict silence. Developing silent speech systems for people who are disabled is another exciting application.