Sound diffusing metasurfaces based on elastic plates and membranes

Abstract

Traditional acoustic diffusers are based on quarter-wavelength resonators, and they are commonly built using slotted panels. The use of this kind of resonators implies that these panels can hardly be manufactured to work at low frequencies due to the resulting high thickness. Recently, the use of resonant metamaterials based on Helmholtz resonators, i.e., metadiffusers, has been proposed to reduce panel thickness. In this work we propose the use of plate and membrane resonators to go one step further in managing sound reflection using ultrathin metasurfaces of deep subwavelength dimensions. Using a 5.7-cm thick panel, a mean diffusion coefficient of 0.8 in the range from 400 to 800 Hz has been numerically and theoretically observed. The potential of resonant metamaterials based on plate and membrane resonators is demonstrated and its limitations discussed. This study provides the guidelines and design tools for prototyping these low-thicknesses panels to generate diffuse reflections.

@inproceedings{RequenaINTERNOISE2021b,
 author = {José Manuel Requena-Plens and Jean-Philippe Groby and Vicent Romero-García and Noé Jiménez},
 booktitle = {EuroNoise 2021: European Congress and Exposition on Noise Control Engineering. Madeira, Portugal. 24-27 October},
 doi = {http://www.sea-acustica.es/},
 editor = {Conference proceedings},
 month = {10},
 organization = {Sociedade Portuguesa de Acústica},
 pages = {1279-1286},
 series = {Oral},
 title = {Sound diffusing metasurfaces based on elastic plates and membranes},
 url = {http://www.sea-acustica.es/},
 year = {2021}
}