High-efficiency sound absorption by a nested and ventilated metasurface based on multi-slit synergetic resonance

Abstract

A nested, sound-absorbing, ventilated metasurface was proposed based on multi-slit synergetic resonance, which could simultaneously achieve high-efficiency (>0.85), sound absorption, and effective (speed ratio >0.67) ventilation in a frequency range of 470–657 Hz. The unit of the sound-absorbing and ventilated metasurface (USAVM) consisted of a ventilation channel and a stepped micro-slit absorber, which could effectively trade-off ventilation and absorption performance. The sound absorption mechanism was revealed via the coupling of the ventilation channel and micro-slit absorber, relying on strong air friction and the slit walls near the resonance frequency. Furthermore, after a parametric study of the USAVM, a compact nested metasurface with a thickness of only 39.1 mm (1/17 wavelength) was constructed using eight parallel USAVMs, with a surface panel area of only 1/7 of the traditional parallel structure. Finally, the sound absorption and ventilation performance of the nested metasurface were verified experimentally. In addition, the absorption bandwidth could be further improved by using more USAVMs. This work provides a new possibility for achieving highly efficient sound absorption with a subwavelength ventilated structure in a low-frequency range that could be applied in buildings or industrial areas.

A subwavelength ventilated structure for efficient broadband sound insulation

“…Muffler ducts are widely applied in gas emission and air exchange systems with fast flow rates [6], and as a key functional structure, the side-branch resonators are communicated through the main duct or slit channel for better performance of sound insulation and absorption [7][8][9]. Ducts with various side-branch Helmholtz resonator (HR) arrays, such as ringtype HRs [10,11], multi-order HRs [12][13][14], double-fishnet plates with HRs in the central layer [15], and circular HRs with shape modification, expand the attenuation bandwidth and transmission loss (TL) values [8,16,17].…”

Ultrathin Space‐Shift Phase‐Coherent Cancellation Metasurface for Broadband Sound Absorption

“…The development of metamaterial provides solutions for designing low-frequency absorbers with a sub-wavelength thickness. [13,14] The basic absorption metamaterial forms include Helmholtz resonators, [15][16][17] resonant membrane/plate structures, [18][19][20] Fabry-Pérot cavities, [12] slit-type absorbers, [21][22][23] and the combined or derived structures by these basic forms, [24][25][26][27][28][29][30][31][32][33] such as the widely used spacecoiling absorbers those combining from Helmholtz resonator and Fabry-Pérot cavity. [24][25][26][27][28] For the metamaterial and metasurface, the design method plays a really important role in achieving the excellent physical performance, especially for widening bandwidth and enhancing amplitude.…”

“…[24][25][26][27][28] For the metamaterial and metasurface, the design method plays a really important role in achieving the excellent physical performance, especially for widening bandwidth and enhancing amplitude. Several structural design methods are available for enhancing sound absorption performance or extending working bandwidth, including parallel synergistic coupling between multi-cells with gradient parameter distribution and weak coupling interaction between units, [12,16,17,19,21,22,34,35] increasing the number of resonance modes in a certain frequency band via the strong coupling interaction among the units to produce more absorption peaks, [18,33] parallel synergistic coupling between different types of soundabsorbing materials / structures, [29][30][31][32] and introducing artificial acoustic soft boundaries for reducing the sound reflection on the interface between the structure and air. [36,37] The most common and effective way to enhance the absorption performance is to use parallel superposition among weak coupling units, which could effectively broaden the working bandwidth to achieve the linear superposition.…”

A compact low-frequency sound absorption metastructure realized by resonators with wavy bending necks

“…Based on the increasing demand of silent environments in daily life and industrial applications, research on broadband low-frequency sound absorption has been receiving more and more attention [1,2]. Conventional sound-absorbing materials, such as porous materials including sound-absorbing cotton and glass fiber [3,4], as well as micro-perforated panels [5], are usually effective in high-frequency sound absorption.…”