Double‐talk detection method with detecting echo path fluctuation

Abstract

AbstractIn the echo canceller, where the normalized least mean square (NLMS) algorithm is used as the adaptive algorithm, the double‐talk disturbs the coefficients of the adaptive filter and increases the probability of howling generation. to cope with this phenomenon, the echo canceller usually is provided with a detector to detect the generation of the double‐talk. the echo canceller is designed to minimize the disturbance by stopping the update of the adaptive filter coefficients when the double‐talk is detected. In the detection of the double‐talk, it is effective to monitor the increase of the residual echo since the double‐talk component masked by the echo can be detected. In this method, however, the residual echo also is increased by the fluctuatio of the echo path and the fluctuation of the echo path should also be detected.This paper proposes a method to differentiate between the double‐talk and the echo path fluctuation, based on the magnitude of the correlation between the input‐containing echo and the echo replica. In other words, the property is utilized that the correlation between the echo replica and the echo is large for the double‐talk and is small for the echo path fluctuation. A double‐talk detection method also is proposed where the power ratio of the residual echo and the echo replica is used as the parameter. It is shown that the double‐talk detection without deteriorating at all the echo elimination can be realized by a structure with a delay preceding the coefficient update operation.