Audible enclaves provide audio without headphones or disturbance

The audio enclaves, developed in research led by Yun Jing, professor of acoustics in the Penn State College of Engineering, are said to work in an enclosed space, like a vehicle, or standing directly in front of the audio source.  

MORE FROM ELECTRONICS

In their study published in the Proceedings of the National Academy of Sciences, the researchers explained how emitting two nonlinear ultrasonic beams creates audible enclaves, where sound can only be perceived at the precise intersection point of two ultrasonic beams.

“We use two ultrasound transducers paired with an acoustic metasurface, which emit self-bending beams that intersect at a certain point,” said corresponding author Jing. “The person standing at that point can hear sound, while anyone standing nearby would not. This creates a privacy barrier between people for private listening.”

By positioning the metasurfaces - acoustic lenses that incorporate millimetre or submillimetre-scale microstructures that bend the direction of sound - in front of the two transducers, the ultrasonic waves travel at two slightly different frequencies along a crescent-shaped trajectory until they intersect, the researchers explained. The metasurfaces were 3D printed by co-author Xiaoxing Xia, a staff scientist at the US Department of Energy’s Lawrence Livermore Laboratory.