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.
