Experimental contribution analysis of external noise components to interior noise of automobile

Abstract

The contribution analysis of various noise sources to interior noise is important, enabling to design an automobile with a low interior noise level. Here, using a modified Cholesky Decomposition (CD), it is proposed to decompose interior noise spectra into multiple spectra, each represents the contribution of a specific noise source to the interior noise. Through an experiment with the two speakers driven by two independent white noise signals, it is shown that the measured noise spectrum can successfully be decomposed into two contributions, each associated with noise radiated from one of the two speakers. Then, an automobile was tested on a road at the speeds of 65 mph and 80 mph. In this experiment, 64 external and 4 interior microphones were used to measure external noise source signals and interior noise signals, respectively. The contribution results obtained by processing the measured microphone signals show the highest contributions of the aeroacoustic sources on the windows and the hood to the interior noise. It was also observed that the contribution of the windows increased as the speed increased and that the higher contribution to the interior noise at a specific seat could be obtained from the window closer to the seat.