Improving Wideband Sound Absorption of Single Layer Micro-perforated Panel Absorber: A Finite Element and Experimental Approach

Traditional porous sound absorbers were the only mode to attenuate excessive sound nearly two decades ago. But due to their degrading acoustic performance at low-frequency range and other practical issues like hygiene, high pressure surrounding, fiber-free feature, etc., micro-perforated panel (MPP) absorbers gradually replaced them. Though MPP absorbers significantly improve over porous sound absorbers, the acoustic absorption is limited to one to two octaves only. In this paper, a 3D-printed MPP absorber is coupled with a thin layer of a natural absorber, such as a jute felt at a rigid wall, to improve the sound absorption characteristics in the desired frequency band. Maa’s theoretical model is employed along with the transfer matrix method to determine the sound absorption of the proposed model. Both finite element and experimental methods were used to validate the results obtained from the theoretical model. Two microphone impedance tube is the main constituent of the experimental setup subjected to random harmonic excitation. Significant improvement is observed in the wideband sound absorption of the above-proposed sound absorber compared to the single-layered MPP absorber.