| 摘要 |
PROBLEM TO BE SOLVED: To obtain a device excellent in sound muffling performance, by effectively increasing sound adsorption loss of a whole frequency band of an object noise to be reduced, while obtaining a high acoustic transmission loss. SOLUTION: In a silencer mounted to an air duct of air-conditioning equipment, at an upper part and lower part in a propagation direction of noise to be reduced Pi propagating in a duct 1, there are provided an upper part resonator X and a lower part resonator Y respectively which have a resonating chamber 3x and a resonating chamber 3y respectively disposed over the whole outer circumference of a pipe body. The resonating chamber 3x of the upper part resonator X is filled with sound adsorbing material 5 in a state where resonating opening 4x is closed from the inside. The resonating chamber 3y of the lower part resonator Y is in an empty state where the sound adsorbing material is not filled in the resonating chamber 3y. The resonating opening 4y is covered with a tensed membrane member 6 that has breathing property and is made of fiber material to prevent flow noise from occurring. The silencer is formed so that an impedance resistance value of the resonator Y becomes small and a peak value of sound absorption loss increased, while maximizing a peak value of an acoustic transmission loss. Accordingly, the device is excellent in sound muffling performance compared with a conventional one. |
