| 摘要 |
A hollow panel (10) includes comprise hollow portions (12) between. front and rear outer sides (11) having a substantially flat plate shape. In the hollow panel (10), the surface density is partially differentiated, whereby a lack of sound insulation due to the coincidence effect at a specific frequency is prevented from occurring. The surface density or the rigidity can be made non-uniform to suppress the lack of sound insulation, by differentiating sectional areas by forming plural kinds of widths of the hollow portions (12), or by differentiating the distances between partition walls (13) or the thicknesses of the walls.
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