| 摘要 |
PROBLEM TO BE SOLVED: To efficiently reduce noise in a vehicle for example. SOLUTION: A noise absorption apparatus 10 comprises a board 100 and a noise absorption material 200. The noise absorption material 200 is formed along an inner wall face 100a of the board 100 formed of a U shape in a cross sectional view, the edge from a part corresponding to the edge end part of the board 100 is folded in the form of a roll, and a pipe line 300 with a spiral shape in a cross sectional view is formed. In addition, a roll-like noise absorption space 400 is regulated by spiral pipe passage 300 in the cross sectional view and the noise absorption material 200 forming the pipe passage 300. Since a cross section area of a direction directed from the outside of the roll of the pipe passage 300 to the inside is gradually reduced, quick change of acoustic impedance in the vicinity of an opening 410 of the noise absorption space 400 is suppressed. In addition, since the pipe passage is formed into the spiral shape in the cross sectional view, noise is efficiently incident on the sound absorption material. COPYRIGHT: (C)2007,JPO&INPIT
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