Subwavelength sound screening by coupling space-coiled Fabry-Perot resonators

TL;DR

This paper presents a novel subwavelength acoustic metamaterial design using space-coiled Fabry-Perot resonators that achieves broadband, omnidirectional sound screening at low frequencies with high attenuation, overcoming diffraction limitations.

Contribution

It introduces a new design of space-coiled Fabry-Perot resonators for broadband, omnidirectional sound screening, significantly reducing metamaterial thickness compared to wavelength.

Findings

Attains tens of dB sound attenuation at low frequencies

Achieves a metamaterial thickness of lambda/15

Demonstrates broadband, omnidirectional sound opacity

Abstract

We explore broadband and omnidirectional low frequency sound screening based on locally resonant acoustic metamaterials. We show that the coupling of different resonant modes supported by Fabry-Perot cavities can efficiently generate asymmetric lineshapes in the transmission spectrum, leading to a broadband sound opacity. The Fabry-Perot cavities are space-coiled in order to shift the resonant modes under the diffraction edge, which guaranty the opacity band for all incident angles. Indeed, the deep subwavelength feature of the cavities leads to avoid diffraction that have been proved to be the main limitation of omnidirectional capabilities of locally resonant perforated plates. We experimentally reach an attenuation of few tens of dB at low frequency, with a metamaterial thickness fifteen times smaller than the wavelength (lambda / 15). The proposed design can be considered as a new building block for acoustic metasurfaces having a high level of manipulation of acoustic waves.