| 摘要 |
PURPOSE:To attain echo cancellation by stopping the identification of an echo path of an echo canceller when the 1st echo cancellation effect is lowered and starting the estimate of the echo path when the effect of the 2nd echo cancellation is equal to the estimated echo cancellation effect thereby applying high speed tracking to fluctuation. CONSTITUTION:If a nearby talker or an echo path fluctuation exists, the echo cancellation effect of an echo canceller 5 operated by an echo cancellation effect operating means 27 is lowered and larger than the estimated echo cancellation effect operated by the estimated echo cancellation effect operation means 28. A comparison means 30 detects it, a decision means 32 stops identification of the echo path of the canceller 5 immediately, compares the echo cancellation effect of an echo canceller 6 operated by an echo cancellation effect operation means 29 with the estimated echo cancellation effect, and decides it as the fluctuation of the echo path when the both are equal, and a control means starts the estimation of the echo path of the canceller 5. When no nearby talker exists, the canceller 5 simulates the echo path to cancel the echo signal. In other case, it is regarded as a simultaneous talking, the identification of the echo path by the canceller 5 remains stopped and the canceller 6 clears the identified echo path at each prescribed time.
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