| 摘要 |
PROBLEM TO BE SOLVED: To detect a double-talk state by using the phenomenon in which a 1st residue signal and a delay residue signal has no level difference of the state is not in the double-talk state, but will have a difference if the state is in the double-talk state. SOLUTION: A 1st residue signal is outputted from a 1st subtracting means 6, which receives delay transmit signal of a 2nd delay means 4 as its addition input and the 1st pseudo-echo signal of a 1st adaptive filter means 5 as its subtraction input. A nondaptive filter means 7 generates the 2nd pseudo-echo signal through convolutional operation between the 1st filter coefficient updated by the means 5 and a receive signal 1. A 2nd subtracting means 8 outputs the 2nd residue signal. by receiving a transmit signal 2 as its addition input and the 2nd pseudo-echo signal of the means 7 as its subtraction input. A 3rd delay means 9 inputs the 2nd residue signal and outputs a 2nd residue signal, having been delayed by a specific time, A detection means 10 inputs the 1st residue signal and 2nd delayed residue signal and detects a double-talk state, when the difference between the both is larger than a prescribed constant, thereby outputting a detection result 11.
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