Practical issues in the use of a frequency-domain delay estimator for microphone-array applications

Abstract

A frequency-domain delay estimator has been used as the basis of a microphone-array talker location and beamforming system [M. S. Brandstein and H. F. Silverman, Techn. Rep. LEMS-116 (1993)]. While the estimator has advantages over previously employed correlation-based delay estimation methods [H. F. Silverman and S. E. Kirtman, Comput. Speech Lang. 6, 129–152 (1990)], including a shorter analysis window and greater accuracy at lower computational cost, it has the disadvantage that since delays between microphone pairs are estimated independently of one another, there is nothing to ensure that a set of estimated delays corresponds to a single location. This not only introduces errors in talker location but degrades the performance of the beamformer. A method for delay estimation and talker location with a microphone array is described that preserves the low computational complexity and rapid tracking ability of the frequency-domain delay estimator, while improving the coherence and stability of the estimated delays and derived source locations. Experimental results using data from a real 16-element array are presented to demonstrate the performance of the algorithms. [Early work principally funded by DARPA/NSF Grant IRI-8901882, and current work by NSF Grant No. 9314625.]