A low-frequency and wideband resonant metamaterial plate with front radial membrane

The various types of metamaterials only have a sound transmission loss (STL) peak at the resonant frequency but are still constrained by the law of mass sound insulation at other frequencies. In this paper, a low-frequency and wideband resonant metamaterial plate with a front radial membrane was designed in order to improve the noise reduction band. Bandgap and STL were calculated by using the finite element method. Studies have shown that in the range of 1 Hz–100 Hz for new metamaterials, the frequency band with STL greater than 30 dB accounts for 75%, and the noise reduction starting frequency is 11 Hz. The mechanisms were investigated by a comprehensive analysis of mode shapes and sound intensity streamlines and then verified by the negative effective density and equivalent mass–spring model. The mechanism analysis shows that there is a wide bridge coupling bandgap between the respective bandgaps of the plate and the membrane. This novel metamaterial not only guarantees the low-frequency and wideband acoustic performance but also alleviates the problem of instability of the noise reduction performance of the membrane material after long-term use, providing a potential application in low-frequency and wideband noise control.