Design of multilayer sound-absorbing composites with excellent sound absorption properties at medium and low frequency via constructing variable section cavities

In this work, multilayer composites composed of ethylene-propylene-diene monomer (EPDM) foams and EPDM perforated plates were proposed to improve sound absorption properties at medium and low frequency. Models of composites with variable section cavities were designed and explored the influence of structural parameters on sound absorption coefficient. Numeral calculations results showed that the sound absorption curves of multilayer composites usually have two peaks in 300–1300 Hz. Compared with the other, the composite composed of one perforated board with variable section cavities and two foams (VFF) shows best sound absorption capacities in low frequency. Two optimization algorithms: artificial fish swarm algorithm (AFSA) and improved particle swarm optimization (I-PSO) were presented to optimize structural parameters of VFF. It is found that the optimization results of I-PSO are better that of AFSA for improving the absorption properties at low medium and frequency. This work provide a simple method and a new idea to improve sound absorption properties of multilayer composites.