Internal Time Delay Calibration of Rigid Spherical Microphone Arrays for Multi-Perspective 6DoF Audio Recordings

Recording navigable or six-degrees-of-freedom (6DoF) audio requires elaborate setups involving multiple microphone arrays capable of recording higher-order Ambisonics (HOA) signals. Rigid spherical microphone arrays (RSMAs) are commonly used for recording HOA. When a number of such arrays are positioned to cover a navigable area, several problems need to be solved: position calibration, orientation calibration, and time delay alignment. There exist several methods addressing each of these problems for arrays comprising pressure microphones. However, these solutions are not directly applicable to a recording setup including multiple RSMAs due to multiple scattering among the spheres. We propose an internal time-delay calibration procedure in the multipole expansion domain for multi-perspective 6DoF audio recording setups comprising multiple RSMAs. We demonstrate the utility of the method via numerical simulations.