Pilot study on wideband sound absorber obtained by adopting a serial-parallel coupling manner

Micro-perforated panel (MPP) absorber has been widely used in noise control and is regarded as a promising alternative to the traditional porous materials. However, the absorption bandwidth of single MPP absorbers is always insufficient to compete with the porous materials. In this paper, aiming at obtaining high absorption over broad frequency band, a compound MPP absorber array adopting the series-parallel coupling manner is proposed and investigated. Firstly, a theoretical model for the normal absorption coefficient of the series-parallel coupled MPP absorber is established based on the electrical circuit analysis. And then measurements of the normal incidence absorption coefficients are carried out to verify the theoretical predictions. The experimental data are in agreement with the theoretical calculation and prove that the composite structure has the characteristics of broadening the absorption bandwidth through a combination of serial and parallel coupling, which may provide a new technique to improve the absorption performance of such type of MPP absorbers.