Low-frequency sound absorption of a metamaterial with symmetrical-coiled-up spaces

A theoretical, numerical and experimental investigation of a low-frequency acoustic absorber (100-600 Hz) is reported herein. The acoustic metamaterial is based on a micro-perforated panel coupled to a multi-cavity of coiled-up spaces that is similar to a symmetrical labyrinth. On considering the visco-thermal losses, the effect of increasing the number of symmetrically coiled-up spaces that determines the peak position of the sound absorption and allows a greater sound energy absorption is discussed theoretically and proven through numerical analysis (FEM). Prototypes were manufactured using 3D printing technology and evaluated in an impedance tube. The results for the sound absorption coefficient acquired in the desired frequency range were greater than 91% with relative bandwidth above 35%, in agreement with the analytical model. Therefore, it is demonstrated that the proposed absorber presents a scale of deep-subwavelength since its total thickness is 0.033 lambda. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study presents a theoretical, numerical, and experimental investigation of a low-frequency acoustic absorber. By improving the acoustic metamaterial design, the absorber achieved a sound absorption efficiency of over 91% in the desired frequency range. The experimental results are in agreement with the theoretical model, validating the design approach for the new absorber.