| 摘要 |
An apparatus for muffling conduit borne air noise includes a casing (1) surrounding a conduit and, within this, a particular volume of sound absorbent material (2), which is designed to provide, at least partially, an open longitudinal passage (3); this passage is surrounded by a surface, which forms the internal surface or equivalent of the sound absorbent material. There is a requirement to reduce noise mainly in the frequency range 50-500 Hertz. Hitherto this has required either a greater thickness of absorbent material or a greater total length of the sound muffler. A new proposed solution consists of the internal surface being made up of at least three surfaces, each arranged to show a convex face towards the passage so that in cross section, the passage (3) is star shaped with at least three points<IMAGE> |
