DSP implementation and performance evaluation of a stereo echo canceler with pre-processing

This paper presents implementation and performance evaluation of a stereo echo canceler with pre-processing. A two-tap time-varying filter located in one of the two channels periodically delays the input signal by one sample. By this pre-processing, the correct echo-path identification is achieved. This stereo echo canceler is implemented by four 32-bit floating-point digital signal processors (ADSP-21062). Experimental results show that the implemented echo canceler can reduce the echo by approximately 25 dB for a white Gaussian signal and by 23 dB on average for a speech signal. The ERLE is not degraded by talker movements in the remote room. The Mean Opinion Score for the implemented echo canceler is 0.55-point and 0.48-point higher than that for the echo canceler based on linear combination for round-trip delays of 100 ms and 600 ms, respectively.