Real-time impulse response estimation based on mirrored virtual sound sources

A fast method to estimate the impulse response of a fixed sound source to a listener at a movable location in a room of arbitrary shape in two dimensions is proposed. The method can be used in video games to calculate the reverberation of sounds placed in a level depending on the position of the listener and can also be used in 3d environments in which the listener mainly moves in two dimensions. After simplifying the geometry of the room using clustering and converting it to a 2d map, early reflections are modelled in detail using an enhanced image source method that takes occlusion into account: the position of the sound source is mirrored on all walls that are hit directly by its sound and virtual sound sources are created at the mirrored locations. This step is repeated recursively to calculate higher order reflections. Based on this pre-computation and the position of the listener, an impulse response of the early reflections in the room is generated in real time. The reflection data is enhanced stochastically using noise bursts to yield a more convincing acoustic effect. The late reflections in the tail of the impulse response are estimated based on the earlier part of the impulse response. (paper)