US Patent 7448353 Intake device of internal combustion engine

A resonator 13 is provided including a resonating body 13 which is vibrated by intake air pulsation in an intake system 5, a volume chamber 14 connected through the resonating body 13 to the intake system 5, and a neck section 16 through which an interior space 15 of the volume chamber 14 is communicated with outside. The interior space 15 of the volume chamber 14 and interior of the intake system 5 are partitioned by the resonating body 13. The resonator is so set that a sound pressure in a certain frequency range is released from the neck section 16 to the outside under vibration of the resonating body 13. With this, the sound pressure characteristics of air intake sound can follow a rise in engine speed.