Engine air intake systems are routinely tasked with delivering a specific target sound thatinvolves meeting an overall noise level and, in many cases, desired frequency content over theentire engine speed range. In order to meet these targets, it is generally necessary to incorporateone or more reactive tuning devices, such as Helmholtz resonators, into the intake system.Traditional devices provide deep attenuation at their designed frequency, but they also introduceundesirable sideband resonances at a higher and a lower frequency. Even after the addition ofseveral devices, it may still not be possible to match the desired intake noise targets due to theirdeep attenuation and sideband amplification. The subject of this work is to introduce anelectronically controlled variable noise control (VNC) device for engine air intake systems that iscapable of adjusting the air intake system’s frequency response as commanded by the engineoperating conditions. The VNC device permits the desired amount of attenuation of peaks in theair intake noise without introducing undesirable sideband resonances. In addition, because thetuning is controlled electronically, the VNC device can deliver a target-specific response usingthe same hardware across multiple vehicles or engine applications.
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