| 摘要 |
PROBLEM TO BE SOLVED: To provide a sound attenuating duct attenuating sound of low-middle-high frequency band. SOLUTION: This duct includes pipes 11, 21, 22, 22B built in an intake system 1 and having first holes 11a, 21a, 22a releasing sound in the intake system 1, and covers 13, 23 covering pipes 11, 21, 22, 22B to attenuate sound and having second holes 13a, 23a overlapping the first holes 11a, 21a, 22a in a circumference direction of the pipe. COPYRIGHT: (C)2009,JPO&INPIT
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