Here's how it works: A woman speaks Dutch into an audio microphone while 11 tiny platinum and iridium needles record her brain waves.
The 20-year old volunteer had epilepsy. Her doctors placed the 2-millimeter-long pieces of metal, each studded with 18 electrodes, into her brain to locate the source of her seizures. A separate research team also found that the electrodes were able to contact parts of her brain involved in the production and articulation spoken words.
This is the coolest part. The researchers ask the woman to repeat the process after she has spoken (called "overt speech"). After a computer algorithmically matches the sounds with her brain activity, the computer algorithms then allow the woman to speak again. She barely speaks, but she mimics the sounds with her jaw, tongue, mouth and jaw. This is "intended speech." She then does it again, but without moving. Researchers asked her to imagine the words.
It was an example of how people talk, but reversed. Real life is a combination of two parts of our brains. One part formulates silent ideas, while another turns them into words. Other parts control movement of the mouth and tongue. These sounds produce the appropriate frequencies for speech. The computers allowed the woman's mind to leap the queue. They were able to register when she was thinking-talking, which is technically "imagined voice" and could play in real-time an audible signal derived from her brain's interpolated signals. These sounds were not as clear-cut as words. Although this work was published in September, it is still preliminary. The simple fact that they took place at the speed of a millisecond shows remarkable progress towards a new use for brain computer interfaces: giving voice to those who are unable to speak.
Anarthria is a condition that results from a neurological disorder, brain injury or other causes. It can be debilitating and frightening but there are ways people can deal with it. Anarthria sufferers might not be able to speak directly. Instead, they may use devices that convert movement from other parts of the body into letters or words. Even a wink can work. A brain computer interface was implanted in the cortex of someone with locked-in syndrome. This allowed them to produce 90 characters per minute using imagined handwriting. It's not perfect, but it is still a good result. A typical English spoken-word conversation takes around 150 words per minute.
It is complicated because, much like moving an arm or cursor, the production and formulation of speech can be very complex. Feedback is what makes it work. It takes about 50 milliseconds between the time we speak and when we hear ourselves speaking. This is what allows people to control their speech quality in real time. It's also what allows humans to learn how to talk.