Patent attributes
A duct of the present invention includes a pair of groove-shaped members which are formed of sound absorbing sheets and a pair of flange portions which are formed of parts of the pair of groove-shaped members that are extended outward from groove opening edges and which are joined in an overlaid state on each other when the pair of groove-shaped members are arranged such that groove openings are opposed to each other. The pair of flange portions includes a seal portion which is formed by crimping the sound absorbing sheets in parts of the flange portions along the groove opening edges and an outer thick portion which is extended outward from the seal portion and which is formed of the sound absorbing sheet thicker than the sound absorbing sheet of the seal portion.