Interior Noise Reduction of Enclosure Using Predicted Characteristics of Porous Material

In this paper, the objective is to reduce the interior noise in a specific frequency band by using the predicted acoustical characteristics of a porous material. To identify the interior sound field of an enclosure, the Green’s function is used and the analytical results are verified by comparing with experimental results. Foamed aluminum is used an absorption material to used as absorption materials to reduce the interior sound pressure of the enclosure. Foamed aluminum is generally known as a metallic porous sound absorption material that has desirable attributes such as lightweight and high absorbing performance. Predicted acoustical parameters of foamed aluminum are used in the analysis to predict sound pressure levels in an enclosure and these results are compared with those of the experiments. To verify the predicted characteristics of the porous material, the analytical results obtained for the acoustical transmission matrix are compared with the experimentally obtained results from a two-microphone arrangement. Based on these results, an appropriate thickness of foamed aluminum is provided for pressure reduction in a specific frequency band.