Computationally-Efficient Simulation of Late Reverberation for Inhomogeneous Boundary Conditions and Coupled Rooms

For computational efficiency, acoustic simulation of late reverberation can be simplified by generating a limited number of incoherent signals with frequency-dependent exponential decay radiated by spatially distributed virtual reverberation sources (VRS). A sufficient number of VRS and adequate spatial mapping are required to approximate spatially anisotropic late reverberation, e.g., in rooms with inhomogeneous distribution of absorption or for coupled volumes. For coupled rooms, moreover, a dual-slope decay might be required. Here, an efficient and perceptually plausible method to generate and spatially render late reverberation is suggested. Incoherent VRS signals for (sub-) volumes are generated based on room dimensions and frequency-dependent absorption coefficients at the boundaries. For coupled rooms, (acoustic) portals account for effects of sound propagation and diffraction at the room connection and energy transfer during the reverberant decay process. The VRS are spatially distributed around the listener, with weighting factors representing the spatially subsampled distribution of absorption on the boundaries and the location and solid angle covered by portals. A technical evaluation and listening tests demonstrate the validity of the approach in comparison to measurements in real rooms.