| 摘要 |
PROBLEM TO BE SOLVED: To display high sound insulation effect in a relatively wide frequency range against a low-frequency sound. SOLUTION: An external member 1 and an internal member 2 are arranged opposite each other across an air layer 3. The internal member 2 has a plurality of through holes 2a, and the thickness (t) of a through-hole 2a part, and the diameterψand aperture rate of the through holes 2a are so set that air passing through the through holes 2a has viscous attenuating operation for a sound of≤30 Hz. The aperture rate of the through holes is preferably≤80 mm, more preferably≥3mm, and much more preferably≤0.5%. The thickness of the through-hole 2a part is preferably≥5 mm. The internal member 2 may be in a variety of shapes, two or more internal members 2 many be provided, and further internal members in various shapes may be combined. The length of the range where the through holes 2a of the internal member are formed is preferably a half as large as the wavelength of the sound to be insulated and the thickness of the air layer 3 is preferably≤1/2 time as large as the wavelength of the sound to be insulated or an integral multiple of a half wavelength. This length can be set by providing a connecting member to partition the air layer 3. COPYRIGHT: (C)2005,JPO&NCIPI
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