| 摘要 |
PROBLEM TO BE SOLVED: To maintain an echo cancel quantity at a high value level even when an echo signal inputted through an echo path to an echo canceler is distorted and a waveform thereof is deformed. SOLUTION: The echo canceler is provided with a first means 11 for varying the level of a receiving side input signal corresponding to an instructed gain, a second means 13 for clipping the receiving side input signal outputted from the first means 11 and inputted to a predictive filter 14 at an instructed threshold level, and a third means 12 for increasing the gain to be instructed to the first means 11 until a state, in which the output level of an addition means 15 exceeds a prescribed value, while only the receiving side input signal is inputted to an echo canceler 10, and setting the threshold level to be instructed to the second means 13 to a level corresponding to the value of the gain in such a state.
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