| 摘要 |
<p>A noise damper, esp. for fitting into a ventilation circuit as in a multi-story building, has a housing rectangular in section. At each end there is a duct connection and the housing is filled with sound absorbent material. At least one passage for air is provided through the housing and this is in the form of a rectangular channel. The passage for the air may consist of two channels separated by a rectangular block of sound absorbing material. The housing is formed fromsynthetic material by vacuum processing and the synthetic material used is self-damping. The sound absorbent material is an open structure polyurethane foam and this also has self-damping properties. The foam is fixed to the inner surfaces of the housing by an adhesive. Dampens noise successfully, esp. in the lower frequencies, without complicated and expensive equipment, or setting up great resistance to the air in the ventilation system.</p> |
