Patent ID: 8792649

Claim:
An echo canceller comprising: an adaptive filter unit that outputs a send-mid signal by eliminating echo from a send-in signal in which transmission voice and echo are mixed; a receiver single talk detecting unit that detects a single talk state on a receiving side using a received signal and the send-mid signal; a first power calculating unit that calculates power of the received signal; a second power calculating unit that calculates power of the send-mid signal; an acoustic coupling amount estimating unit that estimates and updates an amount of acoustic coupling from a power ratio of the send-mid signal and the received signal when the receiver single talk detecting unit detects the single talk state; a residual echo power estimating unit that estimates residual echo power of the send-mid signal from the power of the received signal and the amount of acoustic coupling; a signal-to-echo ratio estimating unit that estimates a signal-to-echo ratio from a ratio between the power of the send-mid signal and the residual echo power; an amplitude suppression coefficient determining unit that determines an amplitude suppression coefficient in accordance with the signal-to-echo ratio; and an amplitude suppression unit that suppresses amplitude of the send-mid signal according to the amplitude suppression coefficient, wherein the residual echo power estimating unit calculates the residual echo power of the send-mid signal by adding a value to the residual echo power estimated from the power of the current received signal and the amount of acoustic coupling, said value indicating a result of multiplying previously estimated residual echo power by a prescribed coefficient β (0<β<1), and wherein the amplitude suppression coefficient determining unit determines the amplitude suppression coefficient corresponding to the signal-to-echo ratio according to the following expression: g ⁡ ( k ) = { 1 b ⁢ ser ⁡ ( k ) c ser ⁡ ( k ) ≦ b 2 c 1.0 ser ⁡ ( k ) > b 2 c g(k): amplitude suppression coefficient ser(k): signal-to-echo ratio b, c: arbitrary constants satisfying b>1 and c>0.