A new algorithm for the estimation of talker azimuthal orientation using a large aperture microphone array

Knowing the orientation of a talker allows a a large-aperture microphone array to select and control cameras better in a teleconferencing situation, improve source-location estimation, and, often, improve beamforming. In 2004, we introduced a baseline algorithm for determining orientation azimuth. Recent testing showed the baseline algorithm behaved poorly when the source was not in the center of the focal area for the array. Here, we describe a second-generation algorithm, A2, that has overcome many of the baselinepsilas short-falls. It still extracts the estimate from microphone energies, but is improved by 1) using a narrow-band, high-frequency analysis, rather than the broad band of the baseline algorithm, 2) using spectral subtraction for uncorrelated noise removal and 3) fitting the processed microphone energies to an ideal model for the direct-wave energy. Most important is that 3) incorporates inverse-square-law effects properly on the direct wave only, which was not the case in the baseline. Results from an advanced simulator are presented to illustrate the issues. Then, A2 and baseline algorithm results are compared using about 60 direct recordings from a human talker in a typical and noisy environment using our 448-microphone array. These show that A2 is a significant improvement.