Mohammad J., Elliott S.

The increasing demand for automotive refinement and improved audio quality in cars motivates the need for better techniques to reduce random road noise. One approach that shows promise for substantial reduction of low frequency road noise is active control, which can be integrated into a car audio system for commercial applications. This paper investigates the effectiveness of various configurations of reference sensors to detect the primary disturbance in a feedforward active control system. The results from a model problem are presented based on a full coupling analysis between the vibration of the car panels excited by multiple uncorrelated sources and the interior acoustic field. Different numbers and positions of force sensors, microphones and accelerometers are used as reference sensors to evaluate the performance of active control. Unconstrained frequency domain optimisation is implemented, together with constrained time domain optimisation, in minimising the mean square errors, and the results of the two approaches are compared. With the correct locations, only a small number of microphones or accelerometers acting as reference sensors are needed to give the best overall performance despite many uncorrelated primary disturbance sources being present. It is also shown that microphones give a slightly better performance compared to accelerometers.