Ultra-open acoustic metamaterial silencer based on Fano-like interference

TLDR

Acoustic metamaterials can attenuate sound while remaining permeable to air, yet existing designs have only a small open area. The study aims to overcome this limitation by demonstrating that a transversely placed bilayer medium with large acoustic property contrast produces Fano‑like asymmetric transmission. The authors design a deep‑subwavelength metasurface unit cell based on this bilayer concept, achieving nearly 60 % open area for air passage while acting as a selective sound silencer. Experimental tests show the unit cell reduces transmitted acoustic energy by up to 94 %, confirming high‑performance, air‑permeable sound silencing suitable for smart barriers and noise‑reduction applications.

Abstract

Recently, with advances in acoustic metamaterial science, the possibility of sound attenuation using subwavelength structures, while maintaining permeability to air, has been demonstrated. However, the ongoing challenge addressed herein is the fact that among such air-permeable structures to date, the open area represents only small fraction of the overall area of the material. In the presented paper in order to address this challenge, we first demonstrate that a transversely placed bilayer medium with large degrees of contrast in the layers' acoustic properties exhibits an asymmetric transmission, similar to the Fano-like interference phenomenon. Next, we utilize this design methodology and propose a deep-subwavelength acoustic metasurface unit cell comprising nearly 60% open area for air passage, while serving as a high-performance selective sound silencer. Finally, the proposed unit-cell performance is validated experimentally, demonstrating a reduction in the transmitted acoustic energy of up to 94%. This ultra-open metamaterial design, leveraging a Fano-like interference, enables high-performance sound silencing in a design featuring a large degree of open area, which may find utility in applications in which highly efficient, air-permeable sound silencers are required, such as smart sound barriers, fan or engine noise reduction, among others.