A broadband multi-resonant sound-absorbing metastructure based on impedance-matching nesting channels

This work presents an impedance-matching double nesting channel composite metastructure consisting of a micro-perforated plate and a porous material (IMDCC). Combining the acoustic properties of the porous material and the nesting channels, a plane wave expansion method is used to establish a theoretical model for studying the sound absorption of IMDCC. Finite element simulations are used to verify the validity of the theoretical model. The proposed absorber with IMDCC shows excellent subwavelength low-frequency ultra-broadband sound absorption capabilities based on nesting channel, reaching perfect absorption at 625 Hz with an absolute bandwidth of 1090 Hz and a thickness of only 1/12.19 of the corresponding wavelength without considering multi-unit coupling. The energy transmission and dissipation reveal frequency-dependent acoustic transmission path properties. Furthermore, different structural and transmission parameters reveal ultra-broadband acoustic absorption properties. Experiments verify that the IMDCC absorber provides multiple-resonance sound absorption and ultra-broadband sound absorption with an absolute bandwidth of 1330 Hz. This work should be useful for the design of new subwavelength low-frequency acoustic absorbing metastructures.