Estimation of Wavefront Arrival Delay Using the Cross-Power Spectrum Phase Technique

In order to provide spatially selective sound capture in a teleconferencing environment, microphone array systems require accurate determination of the location of the desired source. Sound source location in turn relies on estimating time delay of arrival (TDOA) of a sound wave-front across a given microphone sensor pair. The cross-power spectrum phase (CPSP) method M. Omologo and P. Svaizer, ICASSP 94] may be used for TDOA estimation. It is desirable to operate microphone array systems in untreated acoustical environments. Such an environment may produce multipath sound propagation and may contain moderate sources of interfering noise. The TDOA estimates computed using CPSP may become unreliable in such an environment. A strategy is presented to extract reliable TDOA information from the CPSP algorithm. It includes: spectral weighting of the CPSP function based on knowledge of noise and sound source statistics; measuring the accuracy of the CPSP function by examining its shape; and, evaluating the CPSP only when the captured signal has appropriate energy and spectral characteristics. This strategy enables improved performance, and allows more eeective utilization of computing resources in a real-time system.