Simulation and analysis of sound insulation performance of magnetically tunable membrane-type acoustic metamaterials with multi-mass blocks

Abstract Traditional noise reduction materials are often ineffective at suppressing the low-frequency noise radiated by urban transformers. This paper proposes a magnetically tunable membrane acoustic metamaterial (MAM) with multi-mass resonant units, and investigates its sound insulation performance using the finite element method (FEM). The influences of mass block quantity (1–9 pieces) and layout (center, corner, edge) on sound transmission loss (TL) are analyzed. Multiple insulation peaks appear with more mass blocks, and the 9-mass configuration achieves better overall sound insulation yet increases structural mass and mutual vibration constraints. By adjusting magnetic force to tune membrane pretension, the TL peak frequencies can be continuously shifted from low to high frequencies with an expanded bandwidth. This work provides a design reference for tunable low-frequency noise control of power equipment.