US Patent 7203308 Echo canceller ensuring further reduction in residual echo

An echo canceller includes: an echo cancellation part canceling echo included in a near-end input signal; a noise suppression part employing a low-pass filter having a variable cut-off frequency adaptive to power of an input signal, the noise suppression part removing a residual echo component from an output of the echo canceller part; a threshold generation part generating a variable threshold varying in accordance with a power level of a far-end input signal; a determination part making a determination based on a comparison between a power level of the output of the echo cancellation part and the variable threshold; and a processing part performing noise suppression using the low-pass filter on the output of the echo cancellation part when the determination part determines that the power level of the output of the echo cancellation part is lower than or equal to the variable threshold.