A double talk control method improving estimation speed by adjusting required error level

In this paper, we propose a step size control method capable of quickly canceling acoustic echo even when double talk continues from echo path change. This method controls the step size by substituting the difference between the coefficients of a main adaptive filter (Main-ADF) and a sub-adaptive filter (Sub-ADF) for the estimation error in the former. Actually, the number of taps of Sub-ADF is limited to a quarter of that of Main-ADF, and moreover another simplified step size control is applied to Sub-ADF; accordingly the difference quickly approximates the estimation error. The estimation speed can be improved by utilizing the difference for the step size control. We show using speech signals that in single talk the proposed method can provide almost the same estimation speed as the method whose step size is fixed at the optimum one and verify that even in double talk the estimation error quickly decreases.