Abstract: A technology for estimating a delay between a far-end audio signal and a near-end audio signal for acoustic echo cancellation is disclosed. A copy of the far-end signal is stored in a speaker buffer and organized in chunks, and a copy of the near-end signal is stored in a microphone buffer and organized in chunks. Cross correlation is performed on each pair of speaker chunks and microphone chunks based on ?-PHAse Transform (“PHAT”) generalized cross correlation (“GCC”). A peak correlation value can be obtained for each pair of the chunks. Offset values corresponding to the peak correlation values are collected and clustered. A best cluster is selected and the offset value represented by the selected cluster is identified as the estimated delay. Acoustic echo cancellation can be performed on the near-end signal based on the estimated delay.