Controlling the spread of sound and how it bounces off objects is not easy. But by using a few perforated sheets of plastic and a complex algorithm, researchers at Duke University have developed the world's first 3D acoustic cloaking device.
The device escapes acoustic detection by rerouting sound waves in such a way that both the cloak and anything beneath it appear invisible. In future, a scaled-up version of the cloak could be affixed to ships, submarines, or aircraft to help these large objects avoid sonar detection. And in fact, the study was supported by grants from the Office of Naval Research and from the Army Research Office. Alternatively, it could also be used by architects to reduce acoustic effects in buildings or other structures like auditoriums or concert halls.