NEJM: UC Davis speech neuroprosthesis on four Utah arrays decodes a man with ALS's attempted speech with about 97% accuracy

Blackrock Neurotech/Utah array / NeuroPort

A man with ALS implanted with four Blackrock Neurotech Utah arrays (256 electrodes total) achieved 99.6% accuracy decoding a 50-word vocabulary on day one and 90.2% on 125,000 words by day two, maintaining 97.5% accuracy over 8.4 months. He used the speech neuroprosthesis to converse at approximately 32 words per minute for over 248 hours, published in the New England Journal of Medicine.

• Utah arrays record from motor and language cortex; decoding employs text-to-speech vocalization with voice trained to sound like patient's pre-ALS speech.
• 99.6% day-one accuracy on 50-word vocabulary; day two expanded to 125,000 words at 90.2% accuracy; sustained 97.5% over 8.4 months of daily use.
• Patient Casey Harrell: severe speech impairment (7 words/minute pre-implant vs. ~160 words/minute normal conversational speech); 248+ hours of functional use demonstrates reliability and usability.