Simulation of Acoustical Properties of Coupled Rooms Using Numerical Technique Based on Modal Expansion
M. Meissner
Institute of Fundamental Technological Research, Polish Academy of Sciences, Adolfa PawiƄskiego 5B, 02-106 Warsaw, Poland
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In the present study, the acoustic characteristics of coupled rooms were investigated using the computer modelling application based on the modal expansion method. A numerical procedure enables the computation of shape and frequency of eigenmodes, and allows one to predict sound decay times at any point of a room space. Results of numerical simulation have shown that along with a change in a coupling area the effect of a mode degeneration appeared and there are two main reasons for this. First, a mode degeneration is associated with a convergence of frequencies of neighbouring modes with a decrease of coupling area. Another reason for the mode degeneration are variations in a sequence of modes with a change in the coupling area. It was demonstrated that in the coupled rooms several modes exhibit a considerable localization. A degree of mode localization was described theoretically by the "existence surface" of mode and it was found that the localization phenomenon has a great effect on the reverberation process because for some absorbing material distributions it caused the double-slope decay characterized by steep initial and slow late sound decays.
DOI: 10.12693/APhysPolA.118.123
PACS numbers: 43.55.Br, 43.55.Ka, 43.20.Ks