Electronics

Sensor detects sound direction and cuts background noise

Sensor detects sound direction...
The unique distortion from the slice that the sound passes through allows the prototype sensor to separate simultaneous sounds
The unique distortion from the slice that the sound passes through allows the prototype sensor to separate simultaneous sounds
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Researchers test the sensor in a sound-dampening room to eliminate echoes and unwanted background noise
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Researchers test the sensor in a sound-dampening room to eliminate echoes and unwanted background noise
The unique distortion from the slice that the sound passes through allows the prototype sensor to separate simultaneous sounds
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The unique distortion from the slice that the sound passes through allows the prototype sensor to separate simultaneous sounds

Although the ability tends to wane as we get older, the human auditory system is pretty good at filtering out background noise and making a single voice able to be understood above the general hubbub of a crowded room. But electronic devices, such as smartphones, aren't quite as gifted, which is why getting Siri or Google Now to understand you in crowded environments can be an exercise in futility. But now researchers have developed a prototype sensor that’s not only able to figure out the direction of a particular sound, but can also extract it from background noise.

To create the sensor, scientists at Duke University in Durham, North Carolina used a class of materials known as metamaterials, which boast properties not found in nature, and a signal processing technique known as compressive sensing. The disk-shaped device is made of plastic and doesn't have any electronic or moving parts. Rather, it features a honeycomb-like structure and is split into dozens of slices which each feature a unique pattern of cavities of different depths. It is these cavities that distort the sound waves and give the sensor its unique capabilities.

"The cavities behave like sodabottles when you blow across their tops," says Steve Cummer, professor ofelectrical and computer engineering at Duke. "The amount of soda left in thebottle, or the depth of the cavities in our case, affects the pitch of thesound they make, and this changes the incoming sound in a subtle but detectableway."

The sound distortions have specific signatures that relate to thehoneycombed slice it passed over. When the resulting sounds are picked up by amicrophone and processed by a computer, the unique distortions make it possibleto separate noises from one other, even if they were all jumbled together. The sensor,the researchers claim, can even separate simultaneous sounds that originate fromdifferent directions, thanks to the way each sound is distorted.

In tests, three identical sounds were sent from three differentdirections to the sensor prototype. Results showed that it was able todistinguish between these noises with an accuracy of 96.7 percent. The team hopes toscale the 6 in (15 cm) -wide prototype down to a smaller size to allow it to be integrated into various devices. Aside from applications in consumer electronics, its creators say it could also find uses in other areas.

"I think it could be combined with any medical imaging device that useswaves, such as ultrasound, to not only improve current sensing methods, but tocreate entirely new ones," says AbelXie, the study’s lead author. "With the extra information, it should also be possible to improve the sound fidelity and increase functionalities for applications like hearing aids and cochlear implants. One obvious challenge is to make the system physically small. It is challenging, but not impossible, and we are working toward that goal."

The team's paper describing the research was recentlypublished in the Proceedings of the National Academy ofSciences.

Source: Duke University

6 comments
Indiver716
It could also have military or police application for determining the specific location from which any sniper fire might have originated.
wle
it never says what the metamaterials are or what they do.. the remainder of the explanation, would not need any special materials.. so what do the metas do ? what are they? wle
McDesign
Alexa, the Amazon Echo AI, is pretty good at directionalizing sound. There are seven mics around the perimeter, and the kids like experimenting to see if the correct blue indicator mic will light up on their side. Works well, even with conversation background.
Douglas Bennett Rogers
Very cheap to make!
warren52nz
Nice but I just like to add that Google Now on my Samsung Galaxy S3 is excellent at understanding what I say even in noisy, crowded bars. I think stereo mikes + software would help a lot. Our brains are able to extract wanted from unwanted sounds partially because our stereophonic hearing allows us to tell where sounds are coming from so we can focus on a sound more easily.
Kpar
Indiver716 is quite right- the Army has been field testing a sniper direction-finder that has multiple microphones that uses time differential to determine direction. This device promises better performance at a lower cost.