Optimal Mixing Matrices and Usage of Decorrelators in Spatial Audio Processing

In perceptual processing of spatial audio, a typical assumption is that the spatial aspect of a loudspeaker-reproduced sound is determined especially by the energies and the time-aligned dependencies of the audio channels, which are expressed by the real part of the signal covariance matrix, in perceptual frequency bands. In this paper, we propose a generally applicable method to robustly process spatial sound in this domain. This includes an adaptive mixing solution to reach the given target covariance matrix by best usage of the independent components in the input channels, and means to inject the necessary amount of decorrelated sound energy when the target is not achieved otherwise. The method was implemented as a part of a perceptually motivated spatial microphone technique, and numerous further use cases have been identified.