Researchers at the University of Sussex have demonstrated the first ever sound projector that can track a moving individual and deliver an acoustic message. “By designing acoustic materials at a scale smaller than the wavelength of the sound to create thin acoustic lenses, the sky is the limit in new potential acoustic applications.” says Dr. Gianluca Memoli, a lecturer in Novel Interfaces and Interactions at the University of Sussex's School of Engineering and Informatics and who also led the research. "Centuries of optical design can now be applied to acoustics. We believe this technology can be harnessed for plenty of positive applications including personalised alarm messages in a crowd, immersive experiences without headphones, the audio equivalent of special effects."
University of Sussex (Credit): One of the initial prototypes of the telescope, used for testing. The basic principle is that the combined focal length of the two lenses (in grey) depends on their mutual distance. Also in the picture is a speaker (on the right).
The low-cost camera development is based on a face-tracking software that is used to pilot an Arduino-controlled acoustic telescope that focuses sound on a moving target and thus is able to track and command the distance between two acoustic lenses.
"Since acoustic lenses can be 3D-printed for only £100, we wanted a tracking technique that worked on a similar low budget. With a £10 webcam, this is one tenth of standard tracking systems,” says Joshua Kybett, the second-year undergraduate at Sussex who designed the tracking. "In addition, our method has been designed to require user consent in order to function. This requirement ensures the technology cannot be used intrusively, nor deliver sound to an unwilling audience."
University of Sussex (Credit): The current version of Sussex’s acoustic projector. The speaker is contained in the back, together with the tracking camera and one of the acoustic lenses. The part in white is the second acoustic lens in the telescope.
"In our study, we were inspired by autozoom cameras that extend their objectives to match the distance of a target,” says Thomas Graham, the research fellow in the School of Engineering and Informatics who run the measurements and the simulations. "We used a very similar system, with even the same mechanical sound of the motor. I believe our work is also the first step towards hand-held, low-cost acoustic cameras."
Source: Science Daily