Binaural Rendering of Heterogeneous Sound Sources with Extent

In spatial audio rendering applications, it is often desired to render sound sources with a certain spatial extent in a realistic way. While existing methods mainly consider rendering of homogeneously extended sound sources (i.e., with constant radiation characteristics over the extent), rendering of heterogeneously extended sound sources (i.e., with position-dependent radiation characteristics) has barely been discussed in the literature. In this paper, we propose an approach for binaural rendering of heterogeneously extended sound sources. Input to the algorithm is a two-channel signal, which provides information about the position-dependent radiation characteristics of the sound source. Based on a model for an extended sound source with position-dependent energy and spectral content, the target covariance matrix of the binaural output signal is determined. Using a previously proposed optimal mixing approach, a binaural output signal with the desired properties is obtained, ensuring that the spatial characteristics encoded in the two-channel input signal are preserved. The proposed approach is evaluated both objectively and subjectively by comparing it to two homogeneous extent-rendering baselines as well as to simple point source reproduction.