| 摘要 |
PROBLEM TO BE SOLVED: To provide an air intake duct which can attenuate a broadband standing wave and in which excellent sound absorption performance is developed in a specific frequency region in which sound needs to be reduced in particular.SOLUTION: An air intake duct 1 comprises by two half-split bodies made of a fiber mold body being combined includes a cylindrical part 3 and a muffler part 5 provided by branching from the cylindrical part 3. Also, air permeability of a molding wall of the cylindrical part 3 measured by the JIS L1096 A method is 1.0-5.0 cc/cm/sec, and air permeability of a molding wall of the muffler part 5 measured by the JIS L1096 A method is 0.5 cc/cm/sec or less. Furthermore, it is preferable that, when the whole length of the cylindrical part 3 is defined as L, a first high ventilation part having air permeability of 10 cc/cm/sec or more is provided at a position 1/4 of L from one end on a side where air from the cylindrical part 3 flows in, and a second high ventilation part having air permeability of 10 cc/cm/sec or more is provided at a position 3/4 of L. |
