ON FURTHER VALIDATION AND USE OF THE FINITE ELEMENT METHOD TO ROOM ACOUSTICS

Abstract The present paper deals with the finite element analysis of transient vibration of air in rooms and is a sequel to earlier finite element work presented by Craggs. Results obtained from the finite element model of rectangular, triangular and cylindrical rooms are compared with those given elsewhere in the literature. It is shown that the decay constants depend on the type of mode, rather than on the type of wave—axial, tangential or oblique. However, with small patches of absorption it is shown that even for rectangular rooms no such classification exists. Sabine's theory is shown to predict quite accurately the decay constants of oblique modes when the absorptive lining is distributed uniformly across walls which are not curved. Furthermore, results are included for irregular rooms, as well as for regular rooms where the specific admittance of the absorptive lining depends on the frequency of excitation.