Designing and experimental validation of single-layer mixed foil resonator acoustic membrane to enhance sound transmission loss (STL) within low to medium frequency range

This study presents a novel design for an acoustic membrane structure that employs a parallel-arrangement of mixed foil sound resonators to improve sound absorption and insulation capabilities in the low to medium frequency range. The structure is composed of a single layer of parallel-arranged mixed foil wedge-shaped coffers and a bottom flat panel separated by an air cavity. The mixed thickness-based foil resonators are treated as a combination of independent resonators with unique resonance frequency, resulting in improved sound insulation with broadband efficacy. A comprehensive parametric analysis was carried out using the Finite Element Method (FEM) based COMSOL Multiphysics, yielding the anticipated outcomes. The study revealed that the broadband Sound Transmission Loss (STL) can be tailored by varying the thickness of the top and side walls, the bottom plate thickness, and the depth of the rear air cavity. The findings suggest that existing acoustic membrane design can be highly efficient, achieving, and average STL of over 40 dB ∼ 45 dB across the low to medium frequency range of 500 Hz to 3000 Hz. The experimental validation was conducted in an anechoic chamber, and the results were found to be in close agreement with the FEM simulation results. In comparison to conventional uniform foil sound resonator based acoustic membrane structure, this mixed single-layer square wedge-shaped foil resonator based acoustic membrane exhibits outstanding sound insulation performances in the low to medium frequency range, owing to its lightweight structure and availability of conventional manufacturing techniques. This advanced version of the foil sound resonator based acoustic membrane holds immense promise for the use in acoustics and noise control applications across domestic, commercial, and industrial environments.