Thin meta-absorber for low-frequency broadband sound absorption: design, optimization, and experiments

Conventional low-frequency sound absorbers require large thicknesses or complex designs and often suffer from either limited bandwidth or anti-resonance gaps, restricting their use in compact applications. Here, a novel thin meta-absorber has been designed by single- and double-layer micro-perforated panels (MPPs) integrated with space-coiling and Helmholtz resonator (HR) slit-type structures to achieve broadband low-frequency sound absorption. A hybrid series–parallel configuration has developed and analyzed using finite element analysis (FEA) to generate multiple resonance peaks. Besides, Genetic algorithm (GA) has been employed to optimize critical parameters and maximize sound absorption bandwidth performance. Experimental validation of both unoptimized and optimized cases with 41 mm air cavity shows ≤15 Hz deviation which corresponding to <4% of the effective bandwidth, indicating strong agreement with numerical predictions. The optimized meta-absorber achieves a broadband bandwidth of 1840 Hz (360–2200 Hz) with a bandwidth-to-thickness ratio of 44.87, outperforming many existing designs. The proposed thin meta-absorber operates in a subwavelength regime corresponding to λ/23.17, highlighting its compactness for low-frequency noise control and offers significant advantages for aerospace, civil engineering, and transportation applications where both space limitations and acoustic performance are critical design constraints.