The reference signals determine the noise reduction performance of feedforward active road noise control (RNC) systems for cars. In previous research, the reference signals were typically chosen based on the multiple coherence between candidate signals and the primary noise and the effect of system causality on the selection of multiple reference signals has seldomly been studied in detail. In this paper, the upper limit of the noise reduction of a local road noise control system with different reference selections is investigated based on the measured vibration signals at the body joints of an electric vehicle and the primary noise near the target location. In addition, the noise reduction considering the system causality is also analyzed based on the measured impulse response of the secondary path.

Road noise; Reference signal; Electric vehicle; Active noise control