Reverberant Sound Field Analysis of a Rectangular Room by Modal Synthesis Method

Abstract

It is well known that the reverberation time within an enclosed space is dominated by its boundary surface absorption. The absorption can then be interpreted as averaged damping ratio of acoustical modes or a loss factor. The damping ratio can be determined during steady state excitation or during the transient decay or reverberation process. In this paper, acoustical reverberant field is considered as a synthesis of independent acoustical modes with their corresponding damping ratios. Each damping ratio is calculated from the absorption coefficient of the enclosed space considering the wavenumber vector. It is suggested that the consideration for the wave travelling direction in determining the modal decay rate give better results for a simple rectangular room.