| 摘要 |
PROBLEM TO BE SOLVED: To effectively suppress echo even though the tap length of an adaptive filter must be shortened by making the sum of first and second voice input signals, which are inputted from a voice input section through creeping of filtered voice output signals and voice output signals that are not filtered, as the reference signals to determine filter coefficients. SOLUTION: An adaptive filter section 14 is arranged only for a speaker 12. Therefore, output signals to a speaker 11 are X and the output signals to the speaker 12 are H'X. Thus, the creeping signals from a microphone 13 are a sum X(H1+H'H2). The sum signals X(H1+H'H2), which are causes of echo and hauling, are defined as the reference signals 15 and a transfer function H'(=-H1/H2) of the section 14 is determined so that the signals 15 become 0(zero). When a distance between speakers 12 is short, the difference between H1 and H2 is small in general, the convergence of|H1/H2|becomes fast.
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