| 摘要 |
PROBLEM TO BE SOLVED: To provide a sound wave attenuating structure in a tube body for effectively attenuating a sound wave even when the sound wave propagating in the tube body is of a low frequency. SOLUTION: A plurality of areas (for example, areas R1 and R2) are formed in the tube body (for example, a tunnel 1) so that the respective areas R1 and R2 become mutually parallel in the lengthwise direction of the tube body 1 and the mutual areas R1 and R2 mutually different in a sound speed become adjacent to each other. For example, an atmosphere of the areas R1 and R2 mutually different in the sound speed is formed of gases mutually different in a kind. Or the areas R1 and R2 mutually different in the sound speed are formed by making mutual temperatures different. COPYRIGHT: (C)2004,JPO
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