Expanding the strong absorption band by impedance matched mosquito-coil-like acoustic metamaterials

Abstract

A mosquito-coil-like acoustic artificial structure consisting of a spiral channel and a perforated plate with excellent impedance matching is proposed, which can realize strong sound absorption within a certain frequency range. Due to the difficulty in matching the impedance of the single-hole structure with that of the sound propagation medium, the sound absorption should be poor. To overcome this shortcoming caused by the mismatched impedance, some multi-hole microstructures are designed. Moreover, since single-chamber labyrinth can only achieve single-frequency perfect sound absorption, a labyrinthine channel is divided into several chambers with each length distributing by an arithmetic progression gradient. The sound absorption bandwidth can be extended by synergetic coupling resonance among multiple chambers. By selecting different structural parameters including the number of holes, the width of the labyrinthine channel, and the depth of labyrinthine channel, sound absorption of these mosquito-coil-like structures is investigated. The results suggest that the multi-hole structures are helpful in improving the impedance matching, while the synergetic coupling resonance among multiple chambers ensures that the sound absorption coefficient of the structure can be maintained at a high level within a certain frequency range. In addition, some mosquito-coil-like sound absorption structures are fabricated by 3D printing, then the sound absorptions under vertical sound incident conditions are measured, and the strong sound absorption ability in a wide band is experimentally demonstrated. Finally, a method is proposed for adjusting the sound absorptions by proportionally zooming in or out the structure, by which the sound absorptions of the acoustic structure can be effectively shifted to lower or higher frequencies.

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.…”

Enhancing of broadband sound absorption through soft matter

“…The development of metamaterials provides new possibilities for designing low-frequency sound-absorbing structures with sub-wavelength thicknesses, such as resonant membrane-type, [10][11][12] labyrinth, [13][14][15] Helmholtz resonant cavity, 16,17 Fabry-Pe ´rot cavity, 18 and slit structures, 19 as well as secondary structures based on these forms. [20][21][22][23][24][25][26] In summary, there are generally three ways to broaden the absorption bandwidth. The first and most commonly used method is through the parallel-type synergetic among multiple weakcoupling units with gradient parameter distribution.…”

“…The second method involves expanding the number of resonance modes of the integrated structure via the strong coupling interaction between the cells to increase the number of absorption peaks and broaden the working bandwidth. 10,26 The third method involves parallel-type synergistic coupling between different types or multi-scaled soundabsorbing structures, where each type or scale absorbs sound waves in a specific frequency band to achieve the superposition of different absorption bands. 18,20,24,25 The structure size in the thickness or in-plane directions should increase correspondingly to broaden the low-frequency absorption bandwidth using these methods.…”

“…Previous studies have shown that the sound absorption performance can be enhanced either by reducing the impedance mismatch between the structure and the sound propagation medium, that is, achieving impedance matching, or by decreasing the sound propagation speed. 11,18,[26][27][28] This effect can also be achieved via soft acoustic boundaries, which can be defined as an interface where the normal vibration velocity is close to zero, preventing sound wave reflection. Furthermore, recent research has shown that it is possible to artificially construct soft acoustic boundaries using acoustic metamaterials to achieve specific sound wave manipulation.…”

Optimization of Sound Absorption and Insulation Performances of a Dual-Cavity Resonant Micro-Perforated Plate

“…However, the main disadvantage of the microplate is the narrow sound absorption band, which limits its application in practical engineering [7][8][9]. Several scientific researchers have attempted to increase the sound absorption frequency band [10][11][12][13]. Yang et al [14] proposed a novel light sound-insulation composite plates made from aluminum honeycomb cores and microperforated panels and included GSGN film and sawdustboard.…”