INTAKE NOISE REDUCING APPARATUS FOR INTERNAL COMBUSTION ENGINE

[Object] To enhance an intake-noise reducing effect by greatly securing an axial amplitude of an elastic member 14 for intake-air pulsation. [Solution] An intake noise reducing apparatus connected to an intake system of an internal combustion engine includes a bellows-shaped elastic member 14 connected through a communicating tube to an Intake passage. An intake-noise reducing effect associated with an expansion-and-contraction deformation of the elastic member 14 can be obtained in addition to an intake-noise reducing effect obtainable as a Helmholtz-type resonator element. A peripheral wall 14c of the elastic member 14 includes a mountain portion 31 and a valley portion 32 connected through a taper wall 33 to each other. A crest portion of each of the mountain portion 31 and the valley portion 32 is a straight-line portion 35, 36. The straight-line portion 35, 36 is in a cylindrical shape, and hence suppresses a radial displacement which is caused by a change in sound pressure, so that the axial amplitude can be secured by that much.