Acoustic spotlight assembled from modular "Lego"

Optics researchers have for some years been interested in metamaterials, whose structure allows them to manipulate light passing through them. Such materials have been used to create "invisibility cloaks" and other strange effects. Engineers at the universities of Sussex and Bristol have now demonstrated that similar techniques can be used to sculpt sound, which they claim could have important implications for entertainment and public communication.

"Acoustic metamaterials are normal materials, like plastic or paper or wood or rubber, but engineered so that their internal geometry sculpts the sound going through,” explained Gianluca Memoli, a lecturer in novel interfaces and interactions at the University of Sussex and leader of the research. “The idea of acoustic lenses has been around since the 1960s and acoustic holograms are starting to appear for ultrasound applications, but this is the first time that sound systems with lenses of practical sizes, similar to those used for light, have been explored."