Design and analysis of a compact sound absorber made of multiple parallel Helmholtz resonators

In this paper, a compact sound absorber material is proposed and studied for noise attenuation at multiple frequencies using finite element method. The global cylindrical cavity of the material is partitioned into twelve sub- cavities where four are located in the center and one extended neck is connected to each sub-cavity. Each sub-cavity with the associated neck represents a Helmholtz resonator and thus the proposed material design is made of twelve parallel Helmholtz resonators. The sound absorption coefficient and the transmission loss present twelve resonant peaks at different frequencies where the surface impedance is close to the air impedance. The resonant frequencies can be adjusted by the geometrical parameters of the necks and the sub-cavities volumes. The proposed sound absorber can be used in multiple engineering applications to attenuate noise simultaneously at twelve different frequencies.