Improving noise source location using the unwrapped phase method
Yongxin Wang, Corinne M. Darvennes · The Journal of the Acoustical Society of America · 2002
Time Delay of Arrival (TDOA) is the key to using a microphone array for sound source location. The Unwrapped Phase (UP) Method has been used to estimate the TDOA, which is proportional to the slope of the phase of the cross-power spectrum plotted versus frequency. However, reflecting surfaces cause ‘‘jumps’’ in the phase plot. A Zero-Magnitude of Transfer Function (ZMTF) criterion is proposed to automatically pick up the ‘‘jumps’’ to better estimate the TDOA. To verify this, tests were performed in three rooms with different acoustical properties. The sound source consisted of a speaker broadcasting a computer-generated broadband random signal. ZMTF works well in an ordinary room with small reverberation and yields accurate TDOA results. An average error of 0.2% is obtained. In a medium-sized live room, ZMTF identifies ‘‘jumps,’’ and an average error of 1.6% is obtained. In a large reverberation room, however, ZMTF only marginally improved the UP method. The norm of residues and Delay Error were found helpful to evaluate the best results.