A multilayer snowflake resonator metamaterial for low-frequency broadband sound absorption

Abstract Low-frequency broadband sound-absorbing structures with smaller thicknesses are the focus of research in noise control. Based on the principle of Helmholtz resonant cavity and the internal spacer chamber division structure, a multilayer snowflake resonator metamaterial (MLSRCM) is proposed. The MLSRCM model is investigated using theoretical and simulation methods, and it is concluded that the MLSRCM has excellent sound absorption performance in the frequency range of 450–950 Hz with a thickness of only 28 mm. This mainly originated from the parallel connection of multi-units as well as the application of the weak resonance effect of coherent coupling and the full utilization of space. The broadband sound absorption mechanism in MLSRCM is theoretically investigated by analyzing the complex frequency plane. Subsequently, the sound absorption mechanism of the structure is further analyzed in terms of sound velocity and power dissipation density. The results show that the MLSRCM has excellent low-frequency broadband acoustic absorption performance, which provides a reference for the design of new acoustic-absorbing metamaterials with small thicknesses.