Metamaterials assist in 'cocktail party' voice recognition

The device, described in the Proceedings of the National Academy of Sciences, is shaped like a large honeycombed pie with dozens of interlocking slices. The depth of the openings varies in each slice of honeycomb, meaning sound passing over each section has a unique pattern.

“The cavities behave like soda bottles when you blow across their tops,” said Steve Cummer, professor of electrical and computer engineering at Duke. “The…depth of the cavities…affects the pitch of the sound they make, and this changes the incoming sound in a subtle but detectable way.”

When sound passes over the acoustic metamaterials, it gets slightly distorted depending on the depth of the cavities. The sound is picked up by a microphone on the other side of the device, then transmitted to a computer that is able to separate the overlapping noises based on the unique distortion patterns.

According to the team at Duke, the six-inch wide prototype used in testing had a 96.7 per cent success rate in identifying sounds from three different directions. If the technology can be successfully miniaturised, the researchers believe it has a wide range of potential applications, from consumer electronics and medical sensing devices, to hearing aids and cochlear implants.