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.”