AIR-FEED DUCT

摘要

PURPOSE: To provide an air-feed duct which is constituted to reduce the generation of noise in relation to noise of the air-feed duct having frequency distribution differed with an installation state and a use state. CONSTITUTION: An air-feed duct comprises a cylindrical wall body 2a on the inner surface of which a sound absorbing plate 6 is mounted. The sound absorbing plate 6 comprises a pair of electrode plates positioned facing each other; an ENC fluid composition disposed between a pair of electrode plates and having EA particles contained in an electric insulation property medium; and a voltage application adjusting means 20 to apply a voltage between a pair of electrode plates and adjust a voltage.