...thus making future eavesdropping devices infinitely more effective.

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. more