A woman who was left severely paralyzed after a stroke has managed to speak for the first time in decades, thanks to a brain implant and artificial intelligence (AI).
Ann Johnson was only 30 years old when she suffered a stroke in 2005 that left her paralyzed and unable to speak.
18 years after her stroke, an innovative technology has enabled Johnson to communicate again by translating her brain signals into audible words and playing them through a digital avatar.
This technology, developed by researchers at the University of California, San Francisco and the University of California, Berkeley, begins with an implant containing 253 electrodes that intercept brain signals from Johnson’s neurons.
The implant was placed on the surface of Johnson’s brain in areas associated with speech and language. During the surgery to install the implant, doctors also placed a port in Johnson’s head that connects to a cable, facilitating the transmission of her brain signals to a computer bank.
The computer then employs AI algorithms to convert the brain signals into words and sentences, which are spoken through a digital avatar on a TV screen. Essentially, Johnson’s thoughts are translated by the machine and expressed by the avatar, which was modeled after her.
To make the avatar more personalized, researchers utilized a recording of Johnson speaking at her wedding to model its voice after hers. Additionally, the technology translates Johnson’s brain signals into facial movements on the avatar, enabling it to display movements like pursed lips or expressions of sadness or surprise.
According to the experiment’s results, published in the journal Nature, this new technology is faster and more accurate than previous systems that aimed to achieve a similar outcome.
Dr. Edward Chang, one of the study’s authors who also performed Johnson’s surgery, expressed his excitement, saying he was ‘absolutely thrilled’ to see Johnson successfully speak through the avatar.
“There’s nothing that can convey how satisfying it is to see something like this actually work in real time,” Chang said at a news briefing.
The study’s results also reveal that the new technology could convert Johnson’s speech attempts into words at nearly 80 words per minute. Dr. Chang noted that the natural rate of speech is around 150 to 200 words per minute. Additionally, the technology achieved a median accuracy of approximately 75% when Johnson used a 1,024-word vocabulary.
Following the study, Johnson mentioned in a feedback survey that hearing the avatar speak in a voice resembling hers made her emotional.
“The first 7 years after my stroke, all I used was a letterboard. My husband was so sick of having to get up and translate the letterboard for me,” she said.
Johnson also expressed her aspiration to become a counselor and use the new technology to communicate with clients, stating, “I think the avatar would make them more at ease.”