An experimental investigation of active control of road noise employing the weighted error signal to maximize the noise suppression performance at focused control positions

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This study presents the practical implementation and validation of an automotive active road noise control (ARNC) system that can concentrate control efforts on a selected position by employing a weighting factor in error microphone signals. The current ARNC system is designed to uniformly attenuate road noise across the entire seating position in the vehicle cabin, which results in the abandonment of the ability to maximize noise suppression performance in a single seat. It can be expected that the noise suppression performance of the selected position can be further improved by applying a weighting factor to the error signal to concentrate the control effort. However, practical demonstration of the implementation and evaluation of this approach in modern ARNC systems is scarce. To validate this approach, we investigated the influence of weighting factors in the error signals on the noise suppression performance. A practical active control system was implemented in a large luxury sedan, and the noise attenuation performance according to the weighting factor was evaluated based on real driving experiments. The experimental results show that relatively high weighting factors at the selected location can improve the noise attenuation performance. Moreover, it was found that a small weighting factor of 0.01 is suitable to prevent the acoustic amplification of uncontrolled error microphones, as opposed to the extreme condition where the weighting factor is 0.