On Low-Complexity Simulation of Multichannel Room Impulse Responses

In this letter we present a method for low-complexity simulation of multi-channel room impulse responses (RIRs). Low-complexity RIR methods will become inevitable in next generation communication systems having massive amounts of microphones/loudspeakers. For a room with rigid boundaries, we show that proper sampling of the free-field plenacoustic spectrum results in the solution of the wave equation at any position in the room. We show that the spatial aliasing introduced by spectral sampling represents the wall reflections. These wall reflections are usually modelled, at least in low-complexity simulation algorithms, by the creation of virtual free-field sources outside the room, an image source model commonly referred to as the image method. The image method requires O(N3) operations per receiver position, whereas the newly proposed method requires only O(N logN) operations per receiver position.