Patent ID: 8090093

Claim:
An echo canceller comprising: a pseudo echo generation means including an adaptive filter, the pseudo echo generation means generating a pseudo echo signal in accordance with a receiving-speech signal; an echo cancellation means which subtracts the pseudo echo signal from a sending-speech signal, thereby canceling an echo signal from the sending-speech signal; a smoothed sending-speech signal calculation means which calculates a smoothed sending-speech signal from the sending-speech signal, the smoothed sending-speech signal being obtained by smoothing the sending-speech signal; a smoothed receiving-speech signal calculation means which calculates a smoothed receiving-speech signal from the receiving-speech signal, the smoothed receiving-speech signal being obtained by smoothing the receiving-speech signal; a delay time information generation means which obtains delay time information reflecting delay characteristics of an echo path, in accordance with a correlation between the smoothed sending-speech signal and the smoothed receiving-speech signal; an update information generation means which obtains update information indicating execution of updating of the tap coefficients of the adaptive filter or suspension of updating of the tap coefficients of the adaptive filter, in accordance with the sending-speech signal, the receiving-speech signal, and the delay time information; a sending-speech band limiting means which limits a frequency band of the sending-speech signal to supply the sending-speech signal having the limited frequency band to the smoothed sending-speech signal calculation means; and a receiving-speech band limiting means which limits a frequency band of the receiving-speech signal to supply the receiving-speech signal having the limited frequency band to the smoothed receiving-speech signal calculation means; wherein if the update information indicates the execution of updating, the pseudo echo generation means updates the tap coefficients and receives the delay time information as information reflecting the delay characteristics of the echo path to perform processing of the received delay time information; and wherein the pseudo echo generation means generates the pseudo echo signal and updates the tap coefficients by using the sending-speech signal having the frequency band limited by the sending-speech band limiting means and the receiving-speech signal having the frequency band limited by the receiving-speech band limiting means.