Adaptive beamformer for spherical eigenbeamforming microphone arrays

Spherical eigenbeamforming microphone arrays have become a subject of interest in recent years [1-6]. General beampattern design and implementation are simplified due to the decomposition of the soundfield into orthonormal spherical harmonic (SH) “building block” eigenbeams. Eigenbeams are then combined to realize the beamformer. In this paper we present a remarkably straightforward and computationally simple adaptive beamformer. The beamformer algorithm exploits a fundamental non-negativity property of the combination of zero-order SH eigenbeams to realize an implicit constraint for the adaptive spherical eigenbeamformer.