Researchers at the University of California, Davis report that an implanted brain-computer interface (BCI) allows ALS patient Casey Harrell, who cannot speak, to generate synthesized speech from brain activity and to control a computer. The team describes the system in a study published in Nature Medicine. In controlled tests, the BCI produces sentence-level speech with about 99% accuracy. In everyday use, reported accuracy is about 92%, according to descriptions cited by multiple outlets.
The implant has been in place since 2023 and has continued to function with daily use without requiring researchers to be present. Harrell’s home care team is able to set up and use the device. Across more than 3,800 hours of use over roughly two years, the system reportedly supports communication and computer control, and Harrell returns to full-time work. One outlet also reports that the setup enabled nearly 2 million words to be produced, at an average rate of about 56 words per minute.
Researchers frame the work as a step toward BCI systems that remain usable at home over long periods, while maintaining high speech accuracy for patients with ALS-related loss of speech and motor control.