Least-squares Distortionless Response Beamformer in far-field environments with spatial cues preservation

In this letter, some results involving a form of least-squares beamformer are derived based only on directional criteria. In far-field assumptions (i.e., plane wave propagation model for the signals captured), we show that certain factors appearing in the beamformer coefficients calculation, which are usually formulated using complicated integrals, can be computed using closed-form expressions involving familiar, physically meaningful quantities. Next, by resorting to a limiting case, we demonstrate a clear theoretical link between the resulting solution and MVDR beamforming in cylindrically isotropic noise fields. We then discuss a solution to preserve spatial cues if desired which also allows to easily control and modulate the enhancement strength of the beamformer. Some experimental results are finally given in a challenging real-world environment, showing the merits of the approach.