The calculation method and experimental study on acoustic characteristics of micro-perforated panel absorbers with linear-change cavity

Micro-perforated panel absorber (MPA) with linear change cavity can increase the frequency bandwidth of sound absorption, but its theoretical computation results are not in good accordance with the experiment results. A MPA with linear change cavity is divided equivalently into several absorbers with equal width. After the simplification of the model, the absorptivity of each equivalent absorber is calculated by transfer matrix method. By integrating the absorptivity of each absorber, the absorptivity of the whole structure is obtained. The corresponding experiments are carried out to verify the calculations. A comparison is made between electro-acoustic circuit approach and transfer matrix method. The results show that the theoretical calculation results by transfer matrix method agree well with experimental results, which are more close to the experimental results than the calculation results by equivalent electro-acoustic circuit approach.