Broadband low frequency sound absorption using a monostable acoustic metamaterial.

This Letter presents a monostable acoustic metamaterial that has the potential to implement broadband sound absorption in low frequencies. The proposed metamaterial is realized by placing a flexible panel with a magnetic proof mass in a symmetric magnetic field. A theoretical model of the metamaterial is established and experimentally validated. Predictions and measurements demonstrate that the sound absorption peak frequency significantly shifts downwards with the increasing magnetic field. The relative bandwidth of the metamaterial is also broadened with the increasing magnetic field due to its inverse proportionality to the absorption peak frequency.