  We present the signal processing framework and some results for the IEEE AASP
challenge on acoustic source localization and tracking (LOCATA). The system is
designed for the direction of arrival (DOA) estimation in single-source
scenarios. The proposed framework consists of four main building blocks:
pre-processing, voice activity detection (VAD), localization, tracking. The
signal pre-processing pipeline includes the short-time Fourier transform (STFT)
of the multichannel input captured by the array and the cross power spectral
density (CPSD) matrices estimation. The VAD is calculated with a trace-based
threshold of the CPSD matrices. The localization is then computed using our
recently proposed diagonal unloading (DU) beamforming, which has low-complexity
and high resolution. The DOA estimation is finally smoothed with a Kalman filer
(KF). Experimental results on the LOCATA development dataset are reported in
terms of the root mean square error (RMSE) for a 7-microphone linear array, the
12-microphone pseudo-spherical array integrated in a prototype head for a
humanoid robot, and the 32-microphone spherical array.
