Patent ID: 8315380

Claim:
An echo suppression apparatus comprising: an adaptive filter unit that estimates an echo path of a near end, and that generates a pseudo echo signal of a reception signal received from a far end; a subtractor that subtracts the pseudo echo signal from a near-end signal including an echo signal of the reception signal, a near-end sound and a background noise, and that generates an echo-canceled signal as a result of subtraction; a background noise estimation unit that estimates a spectrum of the background noise; a non-linear processing unit that performs spectrum subtraction to subtract the estimated spectrum of the background noise from a spectrum of the echo-canceled signal, and that controls a gain of the spectrum of the echo-canceled signal for each of frequency bands of the spectrum of the echo-canceled signal in response to a result of the spectrum subtraction, thereby obtaining a spectrum of a transmission signal transmitted to the far end; and a threshold calculation unit that calculates a threshold value for each of the frequency bands, the threshold value being used to determine presence or absence of a residual echo in the echo-canceled signal, wherein the non-linear processing unit compares the result of the spectrum subtraction with the threshold value in each of the frequency bands, then controls the spectrum of the echo-canceled signal with a high gain in a frequency band where the result of the spectrum subtraction is higher than the threshold value, and controls the spectrum of the echo-canceled signal with a low gain in another frequency band where the result of the spectrum subtraction is not higher than the threshold value, the low gain being set to lower than the high gain.