Active road noise control in a car cabin using structure-borne sound

This study describes the implementation of an active vibration road noise control (AVRNC) system to reduce road noise in the cabin of a car by using structure-borne sound. An electronic sound generator (ESG) was used as a secondary actuator to make a structure-borne anti-noise and was installed at the cowl panel of the car. Although the secondary path of the ESG was relatively longer than that of a typical acoustic loudspeaker due to the structure-borne sound response. Four 3-axis accelerometers were attached at each wheel hub of the car to capture 12 reference signals of road noise. Only four effective reference signals among them were selected after analyzing the primary paths with multiple coherences. The AVRNC algorithm based on the FxLMS was implemented in a digital controller. The real-time control experiment was conducted during driving with a fixed speed of 60 kph on a straight test road. From the measured results, the road noise at the driver's ear was reduced about 4 dB.