Micro-perforated panel absorber in small-scale cavity

Micro-perforated Panel (MPP) with a backing air gap has been widely used in various noise control applications. Treated as a type of sound absorption material, its acoustic property is usually described in terms of the locally reactive acoustic impedance under normal plane wave incidence assumption. A Micro-perforated Panel Absorber (MPPA) consists of a MPP and a backing air cavity of a finite volume. When integrated to a complex vibro-acoustic environment such as an enclosure, its acoustic behavior will be strongly affected by the surrounding acoustic media to which it is coupled. This paper presents a theoretical tool to investigate this problem. It is shown that the MPPA has to be modeled as part of the system. Analysis shows that the sound absorption efficiency of the MPPA depends on the modal coupling between the enclosure and the MPPA backing cavity, the consideration of which is necessary for accurately predicting the sound field of the enclosure. Experiments are carried out to support the findings.