Particle-filter tracking of sounds for frequency-independent 3D audio rendering from distributed B-format recordings

Six-Degree-of-Freedom (6DoF) audio rendering interactively synthesizes spatial audio signals for a variable listener perspective based on surround recordings taken at multiple perspectives distributed across the listening area in the acoustic scene. Methods that rely on recording-implicit directional information and interpolate the listener perspective without the attempt of localizing and extracting sounds often yield high audio quality, but are limited in spatial definition. Methods that perform sound localization, extraction, and rendering typically operate in the time-frequency domain and risk introducing artifacts such as musical noise. We propose to take advantage of the rich spatial information recorded in the broadband time-domain signals of the multitude of distributed first-order (B-format) recording perspectives. Broadband time-variant signal extraction retrieving direct signals and leaving residuals to approximate diffuse and spacious sounds is less of a quality risk, and likewise is the broadband re-encoding to enhance spatial definition of both signal types. To detect and track direct sound objects in this process, we combine the directional data recorded at the single perspectives into a volumetric multi-perspective activity map for particle-filter tracking. Our technical and perceptual evaluation confirms that this kind of processing enhances the otherwise limited spatial definition of direct-sound objects of other broadband but signal-independent virtual loudspeaker object (VLO) or Vector-Based Intensity Panning (VBIP) interpolation approaches.