A tunable high-order micro-perforated panel metamaterial with low-frequency broadband acoustic absorption

We proposed a tunable high-order micro-perforated panel metamaterial for broadband absorption, in which the energy dissipation modes is reconstructed by the cavity partition plates. Owing to the more degrees of freedom in impedance design, the metamaterial not only obtains multiple perfect absorption peaks with broader bandwidth, but also allows for flexible frequency regulations. By coupling 12 high-order cells, the metamaterial finally achieves a smooth spectrum with 94% average absorption across the range of 300-3200 Hz, which is verified by the simulation and experiment. This metamaterial could have great applications in noise control engineering owing to the extraordinary performance.