Think Before You Speak: How “Mind-Reading” Technology is Giving People Their Voices Back

Think about the last time you spoke to someone. Did you consciously think about the action of speaking? For most people, this movement is subconscious, but that’s not the case for Casey Harrell. 

Casey is an environmental activist who began to lose his voice in 2019 due to the degenerative nerve disease ALS. By 2023, he could no longer speak to his four-year-old daughter and was living in a wheelchair. In hope of regaining his speech, he enrolled in a clinical trial led by UC Davis that year. They installed a neural implant that acted as his voice, reading his brain activity and turning it into speech – a technology known as a brain-computer interface (BCI). BCIs take an input from a person’s brain activity and translate it into a practical outcome. In simple terms, BCIs allow you to control a device just by using your mind. 

These technologies aren’t exactly “reading your mind,” though. They use large amounts of data and pattern recognition to decode the electrical signals that are firing in someone’s brain. First, the device must receive an electrical signal from the brain either through patches attached to the head or implants inside the brain. The device then looks for distinct patterns in the signal that correlate with a certain function. It’s kind of like recognizing a familiar face in a crowded room. Just like how you have a stored memory of what your friend looks like, the BCI has stored data of what brain signals to look for. The same way you can recognize your friend easily and ignore the rest of a crowd, a BCI can detect distinct signal patterns and ignore any background noise. After recognition, this signal pattern is translated into a command that the device then carries out. 

BCI technology helps restore everyday function to people with limited mobility. In Casey’s situation, the brain implant brought his voice back. He thinks of the words that he wants to say, the BCI reads his brain signals, then verbalizes the words out loud using an imitation of his own voice. Although his average speaking speed using the BCI is 56 words per minute, roughly half the speed of an average conversation, it is all done in real time. Casey is grateful to be able to hold conversations, read bedtime stories, and simply tell her how much he loves her. The BCI is also able to help with sending e-mails or texts on a computer, allowing Casey to maintain his full-time job in climate activism. 

3 years’ worth of data collected from Casey’s clinical trial will help scientists develop even more advanced BCIs. The field is no longer limited to just regaining speech or movement. BCIs have helped spinal cord injury patients experience the sensation of touch through a robotic arm. To achieve this, not only does the BCI need to interpret brain signals and carry out an action, it needs to do the opposite process too. The device needs to encode the touching sensation and then send this back as a signal to the brain so that they actually feel the sensation. That’s not a simple task. The technology is still in early stages since capturing nuanced sensations can be complex. A recent study from the multi-institutional Cortical Bionics Research Group showed that a BCI allowed patients with spinal cord injuries to describe 3D shapes. They did this by connecting the BCI to the patient and a robotic hand. Sensors in the robotic hand held different 3D shapes and encoded the sensations of touch. These signals were then sent back to the person’s brain which allowed the patients to distinguish the shapes. It’s an impressive step forward for what BCIs are capable of doing, and as this technology continues to progress, researchers hope that they can further improve quality of life for people living with motor impairments.

So the next time you say something out loud, take a moment to appreciate just how brilliant the human mind and body are. In the split second between a thought and a word leaving your mouth, your brain has planned it out, sent the signals to your nerves, which then activated your vocal muscles. As researchers continue to advance BCI capabilities, we can only hope that it will help more people regain their mobility and independence just like Casey. BCIs not only gave him his voice back, but also a new way to reconnect with the world around him.