A denoising methodology for higher order ambisonics recordings

We propose a denoising methodology for spatial audio recordings acquired with spherical microphone arrays and encoded with Higher Order Ambisonics (HOA). The goal is to suppress the noise field impinging on the microphone array, while preserving the full spatiality of the desired soundfield, produced by an acoustic source of interest within the recording environment. The proposed solution consists of three steps, carried out in the spherical harmonic domain. After estimating the direction of arrival of the source, the source signal is extracted by means of a superdirective beamformer. The resulting signal is finally fed to a set of adaptive filters, that recover the denoised HOA representation by identifying the unknown transfer functions from the source to the array. Simulation and experimental results prove the effectiveness of the method, which is capable of achieving relevant noise reduction while keeping low the distortion introduced by the system.