Theoretical and experimental study on sound absorption performance of Al2O3-polyurethane foam and microperforated plate composite structure

Low-frequency noise pollution in substations has a significant impact on the physical and mental health of workers. Reduction low-frequency noise pollution is an urgent problem to solve for researchers. In this paper, the different structures of Al2O3-polyurethane composites and micro-perforated plate were constructed, and the effects of cavity depth, perforated plate, and foam position on sound absorption properties were comprehensively investigated. The results showed that the position of perforated plate and the arrangement of resonance structure were the two most important factors affecting sound absorption performance. When the sound wave passed through the plexiglass plate–cavity–composites foam–perforated plate in turn, the peak position of sound absorption coefficient was located in the ultra-low frequency range. Meantime, the simulation study showed that the friction between the air column and the cavity wall in the perforated plate can consume sound energy to achieve sound absorption.