Low-frequency broadband absorber with porous material-coupled convoluted resonant cavity

Low-frequency noise exhibits strong penetration capability, while traditional sound-absorbing materials show limited performance in the low-frequency range. To address this issue, a sound-absorbing structure termed the Micro-perforated Resonator with a coiled-space (MRCS) is proposed. The MRCS exhibits deep subwavelength characteristics within the operating frequency range and achieves effective acoustic energy dissipation through spatial coiling and localized resonance. On this basis, a porous material layer is coupled with the MRCS to construct a composite structure, referred to as the Micro-perforated Resonator with a coiled-space with a porous material (MRCSP), thereby further broadening the absorption bandwidth. A finite element model of the MRCSP is established to investigate the sound absorption characteristics of both the MRCS and MRCSP structures. The influence of structural parameters on the acoustic performance is systematically analyzed using the controlled variable method. To validate the reliability of the numerical simulations, impedance tube measurements are conducted on different MRCSP configurations, and the experimental results show good agreement with the simulations. The results demonstrate that the proposed composite structure achieves an average sound absorption coefficient exceeding 0.8 over the frequency range of 190–1200 Hz.