Engineers at the universities of Sussex and Bristol have recently demonstrated sound sculpting by using metamaterials, such a those used to create "invisibility cloaks" and other strange effects in the field of optics engineering.
"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."
The team made use of recyclable materials, such as glass, wood, and 3D printer plastics, and assembled them into modular blocks forming acoustic lenses and devices such as collimators; which can turn the sound from a standard speaker into a directional beam. And the applications mentioned by the team for this are endless. They could reach out to a single person in a crowd, thus there's no need for earphones, this technology might even render them obsolete.
Team member Letizia Chisari explained further, "We are developing a sound capability that could bring even greater intimacy with sound than headphones, without the need for headphones."
Other possibilities include using a sound lens as a receiver to pinpoint alarm noises. Alarms such as these could be useful in for example being able to distinguish between sounds made by an intruder in a house or those made by a pet, or even deliver alarms to people moving in the street (like in the movie Minority Report). It could also be used in indicating faults in machinery wherein with the use of a single microphone, we will be able to listen to small parts of machinery to determine whether everything is working fine.
In entertainment, it can be used to create a three-dimensional sound system within a music venue, to ensure everyone hears the performance at its best. There had been several attempts to improve sound performance prior to this but current surround sound systems in cinemas or concert venues have a very limited "sweet spot" where the optimum acoustic experience can be heard. Because of its modular nature, its small size and the relatively cheap materials used to produce it, Memoli's system should be available to a much wider range of purchasers.
Our prototypes, while simple, lower the access threshold to designing novel sound experiences: devices based on acoustic metamaterials will lead to new ways of delivering, experiencing and even thinking of sound," added team member Jonathan Eccles.
