Adrian Herzog and Emanuël A. P. Habets
IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), UK, 2019.
We present a spatial matrix filtering framework for noise reduction in the spherical harmonics (ambisonics) domain (SHD), which outputs an SHD signal vector rather than one signal as commonly provided by beamforming approaches. We discuss two spatial matrix filtering methods: A multi-beamformer method using known propagation vectors of the desired signal components and a method preserving the directional information in an optimal way. Parametric multi-channel Wiener filter solutions for both methods are discussed and a performance evaluation is conducted. It is shown that the direction preserving method preserves the spatial distribution of the desired sounds and residual noise at the cost of less noise reduction and higher signal distortion when compared to the multi-beamformer approach. Moreover, no spatial parameters have to be estimated.
Binauralized HOA signals with 1 plane-wave source (speech), noise with SNR=3dB and lower bound for matrix filters: -20dB.
For the multibeamforming approach, the desired source propagation vector is incorporated which, in these simulations, is known.
The direction preserving approach only uses prior knowledge of the noise PSD matrix. Therefore, the propagation vectors are not needed for this approach.
Files were generated using the SPARTA AmbiBIN VST plugin .
Playback with headphones is recommended.
 L. McCormack and A. Politis - SPARTA and COMPASS: Real-time implementations of linear and parametric spatial audio reproduction and processing methods, AES Conf. Immersive and Interactive Audio, York, UK, March 2019
 T. J. Klasen et al. - Binaural Noise Reduction Algorithms for Hearing Aids That Preserve Interaural Time Delay Cues, IEEE Trans. Sig. Proc., Vol. 55, no. 4, April 2007