| 摘要 |
PROBLEM TO BE SOLVED: To properly adjust the filter length of an adaptive filter according to the echo signal of each echo path. SOLUTION: A filter length deciding part 21i is set according to an echo path between each speaker 2i and a certain microphone 3m, and acoustic connection quantity Ri constituted of the indirect sounds of the corresponding echo path is calculated from the impulse response of the path or the filter coefficient of the corresponding adaptive filter by each deciding part 21i, and when target acoustic connection quantity is defined as E, and the sum of the filter length of all the adaptive filter is defined as L, PREA=Σi1N(logRi-logE) is calculated by an adding part 24, and Li=(logRi-logE)/PREA is calculated by each filter length calculating part 23, and the Li is defined as the filter length of a corresponding adaptive filter 11i.
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