12. The method for multi-pass echo residue detection of claim 11 , further comprising: determining an amplitude of a maximum correlation result, comparing the amplitude of the maximum correlation result with a predetermined maximum correlation threshold, and determining that the user speech input has an acceptable level of echo residue when the amplitude of the maximum correlation result is equal to or less than the predetermined maximum correlation threshold.
13. The method for multi-pass echo residue detection of claim 12 , further comprising: determining that the user speech input has an unacceptable level of echo residue when the amplitude of the maximum correlation result is greater than the predetermined maximum correlation threshold.