  In this paper, a binaural beamforming algorithm for hearing aid applications
is introduced.The beamforming algorithm is designed to be robust to some error
in the estimate of the target speaker direction. The algorithm has two main
components: a robust target linearly constrained minimum variance (TLCMV)
algorithm based on imposing two constraints around the estimated direction of
the target signal, and a post-processor to help with the preservation of
binaural cues. The robust TLCMV provides a good level of noise reduction and
low level of target distortion under realistic conditions. The post-processor
enhances the beamformer abilities to preserve the binaural cues for both
diffuse-like background noise and directional interferers (competing speakers),
while keeping a good level of noise reduction. The introduced algorithm does
not require knowledge or estimation of the directional interferers' directions
nor the second-order statistics of noise-only components. The introduced
algorithm requires an estimate of the target speaker direction, but it is
designed to be robust to some deviation from the estimated direction. Compared
with recently proposed state-of-the-art methods, comprehensive evaluations are
performed under complex realistic acoustic scenarios generated in both anechoic
and mildly reverberant environments, considering a mismatch between estimated
and true sources direction of arrival. Mismatch between the anechoic
propagation models used for the design of the beamformers and the mildly
reverberant propagation models used to generate the simulated directional
signals is also considered. The results illustrate the robustness of the
proposed algorithm to such mismatches.
