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(1) CV =((Dist A) 2-. (Dist B) 2) / (2L)
where CV is a coordinate value of an acoustic source, Dist A and Dist B are the distances from this acoustic source to two microphone/detectors lying on a line parallel to the axis that is the same as the desired coordinate, and L is the distance between those two microphone/detectors (empirically found to be 100.2 cm) Thus, in conformity with the above discussion, the determination of the location of an acoustic source in a transverse plane requires the employment of three microphone/detectors. With the four available microphone/detectors, each of the four coordinate values can be calculated using two different distance pairs, and this redundancy allows for a certain degree of error correction. The choice of which distance pair to try first is based on the practical consideration of minimizing potential interferences. For the X coordinates, the determining factor is possible head shadowing, and for the Y coordinates, it is possible ambient noise coming frf6m behind the subject (due to the location and orientation of the experimental setup relative to the experimenter and the rest of the laboratory) Table 1 presents the resulting default and alternative coordinate determinants. For example, the default implementation of equation (1) for the Y coordinate of Sp 1 is
(2) Y1 = (D2) 2 (Dl) 2) M2)
and the alternative implementation is
(3) Y1 =((D3)2 (D4)2)/(2L)
..