Estimation methods for sound levels and reverberation time in a room with irregular shape or absorption distribution

The reverberation time of an enclosed space is an important parameter to describe the acoustic quality in enclosed spaces. Mainly due to its simplicity Sabine's equation is normally used even though the considered situations seldom comply with its preconditions: regular room shape, regular distribution of absorption and not to much absorption. For certain groups of applications the prediction errors can be countered by adding empirical corrections, by applying specific interpretations of the input data or by modifications to the Sabine equation. For other applications more sophisticated modelling could be appropriate. But it would be very practical for many applications to have available an engineering type of prediction scheme for the reverberation time or the sound level distribution in enclosed spaces using well-known laboratory data as input. Possibilities for such prediction schemes are developed and discussed in this paper, as back ground information to the informative annexes to the European standard EN 12354, part 6.