| 摘要 |
Apparatus for attentuating noise emitted from an inlet port to a centrifugal fan comprises a panel member which is mounted in spaced confronting relationship to the inlet port and includes a rigid backing member, a facing mounted in spaced disposition from the rigid backing member, partitions dividing the space between the rigid backing member and the facing into a plurality of cavities, and acoustic infill in the cavities. The facing has a plurality of perforation zones, and is formed in each perforation zone with small perforations whereby the facing is rendered acoustically permeable over a limited area only. One wall of each cavity includes a perforation zone of the facing, whereby the cavities constitute Helmholtz absorption cavities. The facing is adapted to face the inlet port and transmit noise for attenuation in the cavities.
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