Example of GCC-PHAT functions before and after de-emphasis. The true TDOAs are −1.1 and 17.7 samples. The vertical line represents the delay of the dominant source. Figure (a) shows the original function. Figure (b) refers to a wide de-emphasis (b = 4.5 and p = 1.5) while (c) shows how changes when a selective notch is adopted (b = 2.5 and p = 0.5). Finally Figure (d) shows the result of applying a very selective function (b = 1.5 and p = 0.2).