| 摘要 |
PROBLEM TO BE SOLVED: To provide a noise reduction device in which noise is reduced with a simple structure by fabricating a cover without adding a reinforcement rib, and in which it is acoustically felt that noise is further reduced by making generated resonance frequency higher. SOLUTION: The noise reduction device includes a casing which is composed of one or more plates for covering a noise source, and the casing has an approximately closed structure connected with the plates, and a noise insulating plate in which an arbitrary curvature is totally or partially provided on at least one face of the plates so as to be swelled to outside or inside. COPYRIGHT: (C)2007,JPO&INPIT
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