An acoustic metamaterial composed of multi-layer membrane-coated perforated plates for low-frequency sound insulation.

Insulating against low-frequency sound (below 500 Hz) remains challenging despite the progress that has been achieved in sound insulation and absorption. In this work, an acoustic metamaterial based on membrane-coated perforated plates is presented for achieving sound insulation in a low-frequency range, even covering the lower audio frequency limit, 20 Hz. Theoretical analysis and finite element simulations demonstrate that this metamaterial can effectively block acoustic waves over a wide lowfrequency band regardless of incident angles. Two mechanisms, non-resonance and monopolar resonance, operate in the metamaterial, resulting in a more powerful sound insulation ability than that achieved using periodically arranged multi-layer solid plates. [ABSTRACT FROM AUTHOR]