Combining Linear Spatial Filtering and Non-linear Parametric Processing for High-quality Spatial Sound Capturing

Flexible spatial sound capturing and reproduction can be achieved with multiple microphones by using linear spatial filtering or non-linear parametric processing. The non-linear approaches usually provide a superior spatial resolution compared to the linear approaches but can result in artifacts due to violations of the sound field model. In this paper, we combine both approaches to achieve a high robustness against model violations and a high spatial resolution. We assume linear spatial filters that approximate the spatial responses of the desired output format and compensate remaining deviations with an optimal post filter. The post filter is computed such that the proposed approach behaves like a linear system when the spatial filters achieve the desired spatial response, and scales towards a non-linear system otherwise. Experimental results show that the proposed approach can significantly reduce distortions of existing parametric processing schemes especially when a sufficiently high number of microphones is available.