Active Control of Simulated Road Noise

Active noise control is a potential method for controlling troublesome low frequency road noise in the passenger cabin of automobiles. In this investigation, the control of simulated road noise in a four door automobile is studied. Active control of road noise requires that the inputs to the controller sense a significant part of the energy causing the noise. Only the coherent energy between the input sensors and the performance microphone is controllable. An investigation is conducted of the control achievable using accelerometers mounted at various positions near the rear wheel of the vehicle as inputs to the controller. The best input sensor location was used with a commercial active noise controller to reduce simulated road noise near the driver's head location. The measured reduction is compared with the results predicted using the coherence. Additional controller simulations were developed to predict and better understand the performance of various controller types in this automobile.