Research on damping coupled double-layer microperforated panel sound absorber

A double-layer microperforated plate (DMPP) absorber that uses a microslit between two plates for damping coupling is proposed and investigated. The absorber forms a microslit of less than 1 mm thickness between the two layers of MPP, so its damping can be provided not only by the microperforations on the plate, but also by the microslit formed between the two plates. The theoretical model of the transfer impedance of DMPP was established by the acousto-electric analogy method and experimentally verified, and the results showed that the theoretical calculation results were in good agreement with the experiment. Then, using the established theoretical model, a comparative study of the sound absorption performance of single-layer MPP and DMPP sound absorbers was conducted, and the results showed that compared with single-layer MPP, DMPP can significantly improve its sound absorption performance by using the damping provided by microslits while reducing its actual plate thickness. Finally, the relationship between the sound absorption performance of the DMPP absorber and its geometrical parameters is investigated, and the results show that there is an optimal value for the improvement of the sound absorption coefficient of DMPP by the microslit thickness when other structural parameters are kept constant, above or below which the sound absorption coefficient decreases.