Active control system for low-frequency road noise combined with an audio system

An active control system for low-frequency road noise in automobiles combined with an audio system is developed as a commercial application for the first time in the world, and installed in a station wagon. The purpose of this paper is to provide an outline of the system and describe the newly developed cost-reduction technology used for it, since the reduction of system costs is a major reason that active noise control technology could successfully be applied in a commercial product. The methods used to reduce costs include utilization of feedback control, implementation by analogue circuits, and common use of audio system speakers. This system reduces low-frequency road noise in the front seat by about 10 dB and improves audio system listening experience while driving.