August 14, 2015

Helping Siri Hear Through a Cocktail Party

The prototype sensor is tested in a sound-dampening room to eliminate echoes
and unwanted background noise.

A new sensor developed at Duke University helps computers separate overlapping sounds.

(August 14, 2015)  People trying to talk to Siri may soon no longer have to look like they’re about to eat their iPhones, thanks to a new technology demonstration that solves the “Cocktail Party” conundrum.

In a crowded room with voices coming from every direction, the human auditory system is incredibly good at homing in on a single voice while filtering out the background jabber.

Computers are not.

A new approach from engineers at Duke University, however, may soon improve their performance in loud environments. The sensor uses metamaterials—the combination of natural materials in repeating patterns to achieve unnatural properties—and compressive sensing to determine the direction of a sound and extract it from the surrounding background noise.

This prototype sensor can separate simultaneous sounds coming from different directions
using a unique distortion given by the slice of “pie” that it passes through.

Once miniaturized, the device could have applications in voice-command electronics, medical sensing devices that use waves, like ultrasound, and hearing aids and cochlear implants.
The study was featured in the Proceedings of the National Academy of Sciences on August 11, 2015.

“We’ve invented a sensing system that can efficiently, reliably and inexpensively solve an interesting problem that modern technology has to deal with on a daily basis,” said Abel Xie, a PhD student in electrical and computer engineering at Duke and lead author of the paper. “We think this could improve the performance of voice-activated devices like smart phones and game consoles while also reducing the complexity of the system.”

The proof-of-concept device looks a bit like a thick, plastic, pie-shaped honeycomb split into dozens of slices. While the honeycomb openings may all look the same, their depth varies from hole to hole. This gives each slice of the honeycomb pie 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 amount of soda left in the bottle, or the depth of the cavities in our case, affects the pitch of the sound they make, and this changes the incoming sound in a subtle but detectable way.”

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