A mind-controlled hearing aid that allows the wearer to focus on particular voices has been created by scientists, who say it could transform the ability of those with hearing impairments to cope with noisy environments.
The device mimics the brain’s natural ability to single out and amplify one voice against background conversation. Until now, even the most advanced hearing aids work by boosting all voices at once, which can be experienced as a cacophony of sound for the wearer, especially in crowded environments.
Nima Mesgarani, who led the latest advance at Columbia University in New York, said: “The brain area that processes sound is extraordinarily sensitive and powerful. It can amplify one voice over others, seemingly effortlessly, while today’s hearing aids still pale in comparison.”
This can severely hinder a wearer’s ability to join in conversations, making busy social occasions particularly challenging.
The hearing aid first uses an algorithm to automatically separate the voices of multiple speakers. It then compares these audio tracks to the brain activity of the listener. Previous work by Mesgarani’s lab found that it is possible to identify which person someone is paying attention to, as their brain activity tracks the sound waves of that voice most closely.
The device compares the audio of each speaker to the brain waves of the person wearing the hearing aid. The speaker whose voice pattern most closely matches the listener’s brain waves is amplified over the others, allowing them to effortlessly tune in to that person.
The scientists developed an earlier version of the system in 2017 that, while promising, had the major limitation that it had to be pre-trained to recognise speakers’ voices. Crucially, the latest device works for voices it has never heard before.
The current version of the hearing aid, which involved direct implants into the brain, would be unsuitable for mainstream use. But the team believe it will be possible to create a non-invasive version of the device within the next five years, which would monitor brain activity using electrodes placed inside the ear, or under the skin of the scalp.
In theory, Mesgarani said, the device could also be used like a pair of audio “binoculars” to covertly listen in on people’s conversations, although this was not the intended application.