Abstract:a new de-cross-correlation preprocessing idea based on time axis perturbation method (TPM), which utilized the fact that hearing perception is not sensitive to the phase distortion of a speech signal, was proposed to solve the non-unique problem (NUP) in multi-channel acoustic echo cancellation (MCAEC). TPM-based frame time shifting (TPM-FTS) linear method and TPM-based frame expanding compressing (TPM-FEC) nonlinear method were mainly explored. Analysis and experiment showed that, under a condition of the same hearing allowance to the preprocessed speech outputs, both TPM-FTS method and TPM-FEC method have a much better de-cross-correlation performance in comparison with the conventional de-cross-correlation nonlinear preprocessing methods based on amplitude perturbation (APM). TPM-FEC has a more regular rule to follow for the decision of the values of its controlling parameters than TPM FTS, but TPM-FTS has a much easier operation for real-time implementation than TPM-FEC.