| 摘要 |
PROBLEM TO BE SOLVED: To provide a silence for an air-conditioning duct to reduce the occurrence of noise throughout a range extending from noise in a low frequency area to that in a high frequency area. SOLUTION: In a silencer for an air-conditioning duct located in the flow passage L thereof and reducing the occurrence of noise propagating the flow passage L, a peripheral wall surrounding the flow passage L is provided with a laminate 3 formed such that a film 7 is stretched on the outside of a sound absorbing material 6b and porous plates 5 are situated with a cushion material 6a nipped therebetween, and a substance to transmit noise and prevent leakage of air is used as the film 7. Noise in a high frequency area is absorbed by the sound absorbing material 6b and, since noise in a low frequency area is radiated to the outside through the holes of the porous plate 5 and diffused, and even when the device is decreased in size, a sufficient noise reducing effect is expected. |
