| 摘要 |
PROBLEM TO BE SOLVED: To provide a sonic velocity control member capable of securing stably quality as an industrial product, by explicating a correlation between a physical property of a porous member and an acoustic characteristic thereof. SOLUTION: A heat capacity C and a through-flow resistance R satisfy Expression (1) and Expression (2), in the sonic velocity control member. Expression (1): C>1.2×10<SP>3</SP>(C=D×Cm) and Expression (2): R>F/42.9, where D represents a bulk density of a structure, C represents a specific heat of the structure, and F represents a frequency of a desired sound wave reduced in a sonic velocity. COPYRIGHT: (C)2009,JPO&INPIT
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