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Method to Estimate the Acoustic Center of Directional Sources and its Psychoacoustic Evaluation

The effective acoustic center (AC) has multiple definitions including: (a) the position of the virtual point source from which sound pressure varies inversely as distance, (b) the point from which the approximately spherical wavefronts appear to diverge when observed in a region around the observer, (c) similar to the previous two definitions but also considering phase. In all 3 cases, only one frequency is considered. In this paper, the position of the acoustic center is estimated by using the time delay between two distinct orientations of a loudspeaker source, direct-facing and sideways-facing, in order to approximate the acoustic center position relative to the rotation axis. If the propagation times of both paths are equal and thus the time delay between both paths is zero, it is assumed that the loudspeaker rotates around the acoustic center. The time delay estimation is based on the phase information calculated by the Generalized Cross Correlation Phase Transform (GCC-PHAT) method. Measurements were carried out in an anechoic environment as well as in a room with reverberation. The technical analysis revealed that the acoustic center can be estimated based on only two consecutive recordings and that the GCC-PHAT method performed very well under reverberant conditions. A listening experiment with anechoic binaural recordings demonstrated that using the estimated position of the AC for low frequencies leads to a source position perceived as stable for loudspeaker orientation up to 85°.

JAES Volume 66 Issue 12 pp. 1062-1071; December 2018
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