Engineering Coiling‐Up Space Metasurfaces for Broadband Low‐Frequency Acoustic Absorption

Abstract

Acoustic metasurfaces based on microperforated panels and coplanar spiral tubes are proposed to realize acoustic absorption in the low‐frequency range, which are composed of holes and an in‐plane coiling‐up channels. Herein, the deep‐subwavelength metasurfaces are developed based on nesting damping subchannels for dual‐band or broadband acoustic absorption in the low‐frequency regime. The absorption properties of the proposed metasurfaces are theoretically and experimentally studied. At the resonant frequencies, high acoustic absorption is observed at deep‐subwavelength scale (the thickness of metasurfaces is smaller than λ/50). The measured results show that both dual‐band and broadband metasurface‐based acoustic absorbers are realized at around 300 Hz, in good agreement with theoretical predictions by properly designing the profile of the holes and channels. Furthermore, the measured acoustic impedances are presented as effectual quantity revealing the dual‐band and broadband feature of the metasurface absorbers. The design herein can be further applied to extra broadband absorption with a compact metasurface in future.