Effects of the backing cavity on the acoustic absorption of a microperforated panel absorber

The attractive features of the microperforated panels (MPPs) make them an alternative to conventional fibrous materials for acoustic absorption in environment where high hygiene standards are required. To evaluate the absorption effect, a model for the MPP with a backing cavity, i.e. MPP absorber (MPPA), has to be developed. Usually, a MPPA model is developed based on the one-dimensional assumption such that only the backing cavity modes associated with the depth contribute to the resonance absorption. For the real case, however, a MPPA is of finite-size and the modes associated with the lateral dimensions of the backing cavity will contribute to the coupling as well. In this paper, efforts are made to understand the coupling of different types of backing cavity modes to the MPP. It is found that the participation of those backing cavity modes not only influences the acoustic property of the MPPA but is also possible to deteriorate the absorption performance.