2026-05-21 ペンシルベニア州立大学（Penn State）
Researchers from Penn State have created a 3D-printed speaker covering that can tightly focus sound waves into a tiny point in space, like a magnifying glass focusing a beam of light. Credit: Provided by Jee Woo Kevin Kim. All Rights Reserved.
＜関連情報＞
- https://www.psu.edu/news/engineering/story/3d-printed-speaker-cover-can-focus-audio-private-sound-spot
- https://ieeexplore.ieee.org/document/11503441
メタサーフェス対応パラメトリックアレイスピーカーによる可聴焦点スポット生成 Audible Focal Spot Generation via a Metasurface-enabled Parametric Array Loudspeaker
Jee Woo Kim; Jiaxin Zhong; Yun Jing
IEEE Transactions on Ultrasonics Published:01 May 2026
DOI:https://doi.org/10.1109/TUSON.2026.3689544
Abstract
Parametric array loudspeakers (PALs) produce highly directional sound beams but are constrained by poor low-frequency performance and unwanted low-path attenuation. Existing beam focusing engineering alleviates these limitations but relies on active phased arrays, which are costly and requires complex hardware for practical applications. Here, we present a passive acoustic metasurface (AMS) lens that enables broadband focusing of the audible beam generated by an ordinary PAL. The AMS is constructed from Fabry-P´erot-based annular unit cells, whose width is smaller than the carrier ultrasound wavelength, allowing fine spatial phase control for achieving tight focusing. Both simulations and experiments confirm the generation of strongly localized audible focal spots, with measured full-width at half-maximums (FWHMs) below 30mm axially and 6mm laterally across a wide frequency range from 500 Hz to 4 kHz. Our passive AMS design delivers stronger low-frequency output and steeper path attenuation than conventional PALs, supporting private delivery in public installations, vehicles, healthcare, and immersive environments. Unlike phased-array PALs that rely on computationally intensive beamforming and complex control hardware, the passive AMS offers a compact and low-complexity alternative for direct applications.
