Composite acoustic metamaterial for low-frequency sound insulation based on multi-cell coupling

The broadband suppression of low-frequency noise in ship constitutes a critical engineering challenge, as it is directly related to acoustic stealth, vibration and noise control and equipment safety in marine vessels. This study presents a novel multilayer composite acoustic metamaterial comprising membrane, Helmholtz resonator, coiled channel and air cavity. The sound insulation mechanism of the proposed structure is investigated through finite element simulations using COMSOL Multiphysics and experimental validation. The study reveals the influence of parameters such as the stacking sequence of the constituent cells, membrane thickness, neck length and neck diameter of Helmholtz resonator and cavity depth on the sound insulation performance. Furthermore, the sound insulation effect resulting from coupled multi-cell synergistic interaction is explored. Experimental results demonstrate that the proposed composite acoustic metamaterial achieves an average sound transmission loss of 55 dB. The composite structure achieves high-efficiency sound insulation within 100–1000 Hz, with thickness equivalent to merely 1/70th of the acoustic wavelength at 100 Hz. The proposed composite acoustic metamaterial meets the dual requirements of low-frequency broadband sound insulation and lightweight configuration for practical engineering applications, thereby providing effective technical support and data support for low-frequency noise control in ships.