Researchers from Pennsylvania State University have developed a speaker cover that focuses sound from PALs into a tiny focal spot, resulting in isolated sound that cannot be heard from even a short distance away from the targeted area.
According to the researchers, the 3D-printed cover can not only tighten the acoustics from PAL speakers, but also improves the bass performance of the speaker. This is notable due to the typical bass drop-off associated with most directional audio systems.
“To develop an acoustic metasurface, we use a large surface that works like a lens focusing a beam of light,” says Yun Jing, acoustics professor and the paper’s corresponding author. “The surface modulates sound waves in such a way that they converge at a central point after leaving the speaker, allowing us to focus the audio into a precise area.”
The results can be seen in the video above, where moving a microphone away even a few inches from the focal spot results in a dramatic decrease in volume.
“The acoustic metasurface is about six inches in diameter — around the size of a small plate — and can be applied directly onto the surface of any PAL,” says Jee Woo Kevin Kim, an acoustics doctoral candidate and first author on the paper. “We believe this holds great commercial potential, as companies would just need a 3D-printer or a plastic mold to mass produce these components.”
