Sound transmission loss characteristics of Membrane-type Acoustic Metamaterials based on piezoelectric shunt circuits

Abstract Conventional Membrane-type Acoustic Metamaterials (MAM) achieve good sound transmission loss (STL) at low frequencies. But the MAM can only produce a single narrowband peak. To enable broadband low-frequency insulation, the integrating piezoelectric shunt circuits are proposed into MAM. Three circuit configurations (negative capacitance, amplification, and combined negative capacitance-amplification) are systematically investigated. First, finite element simulations were conducted to calculate the STL curves for the three circuit configurations. The results demonstrate that the negative capacitance circuit effectively compensates for the inherent capacitive reactance of the piezoelectric sheet, while the amplification circuit enhances the local resonance capability through voltage amplification. The negative capacitance-amplification circuit synergistically combines both advantages, achieving a peak sound insulation of 58.72 dB at 120 Hz while substantially broadening the effective sound insulation bandwidth. Furthermore, to investigate the influence mechanism of the piezoelectric shunt circuits, the equivalent bending stiffness model was developed. The abrupt variations in equivalent bending stiffness induce an anti-resonance effect, which enhances sound wave reflection, thereby improving the sound insulation performance of the MAM in specific frequency bands. Finally, the simulation results were verified through experiments.