ACTIVE SILENCER

摘要

PROBLEM TO BE SOLVED: To reduce noise by emitting a silencing signal from one speaker through branch pipes to small-caliber ducts formed by dividing a large-diameter duct to a plurality. SOLUTION: A first noise detecting means 11 is arranged on a large-caliber duct 6 side arranged on a noise source side and the large-caliber duct 6 is communicated with the silencing ducts 7 divided to a plurality. A second noise detecting means 12 is, arranged on the downstream side of the silencing ducts 7 and the silencing ducts 7 are provided with silencing signal output means 14 through the branch ducts 13. The silencing ducts 7 are formed as interference sections and the interference sections are divided to plural spaces. The silencing ducts 7 are divided to a plurality by branch plates 7b and the branch sides of the branch ducts are connected thereto so as to bestride the dividing plates.