To provide a device capable of appropriately controlling an adaptive operation by setting the threshold for sound/silence determine of a transmission signal from a ratio between values associated to the power of a reception signal and a transmission signal and determining the sound/silence of the transmission signal from a value obtained by adding a margin to the ratio of the values associated with the power of the reception signal and the transmission signal and from the threshold for sound/silence discrimination of the transmission signal, which is set.

A double talk detector receives a remaining, difference signal e(n), a reception signal x(n) and a transmission signal y(n) from terminals 20, 21 and 22 and calculates respective powers Pe(n), Px(n) and Py(n) by power detectors 23, 24 and 25. The power Px(n) is compared with a silence detection threshold XTH of the reception signal in a comparator 28. When the reception signal is discriminated to be silent, a signal O is sent to a threshold setting means and an adaptation inhibition signal generation part 35. When the reception signal is discriminated to be a sound, a signal 1 is sent. The adaptation inhibition signal generation part 35 receives the discrimination results of the comparators 28, 33 and 34 and outputs the signals of adaptation inhibition and inhibition release to a terminal 36.