To use a coefficient of an adaptive filter which is currently the most suitable.
A plurality of adaptive filters (3-n) have different update quantities set and filter coefficients are determined at any time according to the set update quantities. The coefficient of an adaptive filter (3-n) having a large update quantity converges fast, but is apt to improperly change, and the coefficient of an adaptive filter (3-n) having a small update quantity is not apt to improperly change, but converges slow. An adaptive filter decision means 5 calculates echo suppression quantities of the plurality of adaptive filters (3-n) respectively and decides whether the calculated echo suppression quantities meet a predetermined standard. A coefficient setting means 6 selects the adaptive filter (3-n) which is currently the most suitable according to decision results of the adaptive filter decision means 5 and sets it as a half-fixed filter 4. Consequently, the filter coefficient which is currently the most suitable is selected.
KATO YASUHIKO
KIHARA NOBUYUKI
KISHI HIDEKI
SAKURABA YOHEI
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