| 摘要 |
A noise attenuation device comprising a first tube for receiving an acoustic signal, a first housing defining a first cavity between a first surface and a second surface, the first tube being coupled to the first housing at the first surface for conducting the acoustic signal into the first cavity, wherein one end of the first tube contacts the first surface at a first region with a first area, a second housing defining a second cavity between a first surface and a second surface, and a second tube coupled between the second surface of the first housing and the first surface of the second housing for conducting the acoustic signal between the first cavity and the second cavity, wherein one end of the second tube contacts the second surface of the first housing at a second region with a second area, wherein the first tube, the first housing and the second tube form a filter structure and the area of the first surface of the first housing is greater than the first area and the area of the second surface of the first housing is greater than the second area.
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