Robust high-efficiency and broadband acoustic absorber based on meta-molecule cluster sets

We demonstrate a broadband high-efficiency acoustic absorber with subwavelength thickness. The acoustic absorber is based on meta-molecules can achieve near-perfect absorption. By adjusting structural parameters of meta-molecules, the acoustic absorber can offer absorption tenability within a wide frequencies range under a fixed thickness. Therefore, we can realize broadband and multiband absorption by assembling cluster sets based on different meta-molecules. Moreover, an optimization method for effectively filling the ‘acoustic absorption valley’ is ascribed to utilize the coupling effect between porous materials and meta-molecule cluster sets. Theoretical analysis, numerical simulations and experimental measurements show that the absorber can realize sound absorption of broadband and high-efficiency. Our design may offer applications in noise reduction and room acoustics.