| 摘要 |
PROBLEM TO BE SOLVED: To provide a simple structure which decreases the noises of all frequency ranges of ducts of air feed and discharge routes, ducts of internal combustion engines, etc., does not change suction resistance as far as possible and has a high attenuating effect. SOLUTION: This sound absorbing duct is constituted by connecting a cylindrical base duct 1' and an expansion duct 1 made larger in the bore than this base duct 1' in a ventilation direction A. A sound absorber 2 is installed in this expansion duct 1. This sound absorber 2 occupies 10 to 50% of the sectional area of the internal space of the expansion duct 1. |
