DOA Estimation Improvement for Low-Frequency Symmetric 3-D Arrays in Reverberant Environments

Special attention is now being paid to the processing of microphone array signals‎. ‎Sensors located in the array receive the source signal at different time intervals‎. ‎In order to find the direction of source‎, ‎the time difference measurement algorithms‎, ‎which are based on the calculation of cross correlation function‎, ‎calculate the correlation between the outputs of the array sensors‎. ‎The maximum peak of the correlation function indicates the time difference of the sensors to each other‎. ‎Then‎, ‎the source signal orientation will be estimated by using the direction of arrival estimation algorithms based on the calculation of the time differences‎. ‎When the signal propagates in a direct path‎, ‎the cross-correlation function is efficient to measure the time differences‎. ‎However‎, ‎in the case the signal propagates in multipath medium‎, ‎the generalized cross-correlation functions will be used due to the presence of multiple peaks in the cross-correlation function‎. ‎The Phase Transform method‎, ‎which is a family of generalized cross-correlation methods‎, ‎yields better results than other methods‎. ‎Nevertheless‎, ‎it performs poorly at low SNRs‎. ‎In this study‎, ‎we add a modification factor to the weighting function of the Phase Transform method‎. ‎In the following‎, ‎the results of time differences obtained from the proposed method are then applied to different DOA methods‎. ‎In the simulations‎, ‎it was observed that the particle swarm optimization method offers the least error among the DOA methods‎, ‎so that the error values of backazimuth and elevation decreased by about 3 degrees and 2 degrees‎, ‎respectively for the factor of 0.65 at low SNRs‎.