Design and study of broadband sound absorbers with partition based on micro-perforated panel and Helmholtz resonator

Micro-perforated panel (MPP) absorber has various merits, so it has great potential for application in the field of noise control. In this paper, the cavity with a variable section partition was designed to solve the broadband sound absorption problem of MPP. Three types of sound absorbers were developed with subwavelength thickness based on the cavity: Micro-perforated panel with built-in Helmholtz resonator (MPPHR), single-layer and double-layer micro-perforated panel backed by the cavity (SL-VMPP and DL-VMPP, collectively referred to as VMPP). The absorption characteristics of three sound absorbers with various partition parameters were investigated by COMSOL Multiphysics software. Furthermore, three types of absorbers were optimized with particle swarm optimization (PSO) algorithm for a superior absorption performance. Finally, the experimental results demonstrate predicted improvements in broadband sound absorption levels when compared to conventional MPP absorber: The MPPHR with a thickness of 32 mm (∼λ/18 at the first resonant frequency) has a half absorption band of up to 1294 Hz, which is nearly 500 Hz wider than the conventional MPP with equal cavity depth. The optimized SL-VMPP and DL-VMPP have an absorption level of at least 80 % in the frequency range of 794–1614 Hz and 632–1954 Hz, respectively.