High-efficiency broadband absorption/reflection integrated lossy acoustic metasurface via embedded microperforated wall

Period phase gradient metasurface plays a great role in promoting the innovation of acoustic application devices. However, harnessing the internal thermal viscosity of the period phase gradient metasurface to realize sound absorption and non-reciprocal transmission faces the narrow working frequency band and uncontrollable efficiency. In this paper, we propose a lossy metasurface by embedded microperforated walls to realize sound redirection and absorption with high efficiency than 90% simultaneously. The phase modulation is realized using an opening channel, which can cover the 2 π phase range in a broadband frequency range by changing the channel depth. The loss introduced by the microperforated walls can achieve efficient sound energy dissipation when negative reflection occurs. The functions can be switched between wave redirection and wave absorption by rotating the metasurface. In addition, this metasurface can redirect the incident wave below −10° and absorb the incident wave above 25° over a wide frequency range from 1500 to 6500 Hz. The simulation and experiment results of our design are in excellent agreement. This research provided a new bridge to integrate wave redirection and absorption with microperforated walls and may have potential applications in acoustic sensing, sound source identification, and mechanical fault diagnosis.