Numerical models for predicting absorption/insulation performance of acoustic elements

Abstract

WIth a great improvement of computer resource availability, numerical analysis is widely used to investigate acoustic characteristics of various materials. A further expectation will be to predict absorption/insulation performance of acoustic elements used for buildings, automobile and so on, which can be the alternative to the actual measurements. This paper presents general numerical models for predicting the absorption coefficient and the transmission loss of acoustic elements with arbitrary shape and material composition. The features of the models are: 1) A test sample is mounted in the cavity or aperture on a thick rigid baffle: 2) FEM is employed for the materials and the air in the cavity, and coupled with sound fields out of the baffle by BEM: 3) Acoustical indices are calculated from the incidence power and the absorption/transmission power on the interfaces. Numerical simulation demonstrates the oblique incidence absorption coefficients and transmission losses of single layered materials. The influence of the area and depth of the cavity/aperture are discussed in comparison with theoretical values for the infinite area. © 2013 Acoustical Society of America.