Membrane-type acoustic metamaterials (MAMs) are capable of attenuating sound by resonating at specific frequencies, but they typically exhibit narrow absorption bandwidths. To address this limitation, the present study explores a multilayered periodic configuration of MAMs aiming at broadening the range of absorption spectrum. By periodically stacking MAMs, the phase differences in the transmitted sound waves shift the effective resonant frequencies of each layer, resulting in multiple absorption peaks. This approach is particularly effective in the low-frequency region, which is often difficult to address with conventional materials. A commonly used membrane-type unit was adopted for structural design to demonstrate the feasibility of this approach. The findings suggest that periodic stacking of MAMs offers a promising strategy for achieving broadband sound absorption with compact structures.
Hamaguchi et al. (Wed,) studied this question.