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In this paper, the vibro-acoustic transmission characteristics are investigated in the view point of the airborne noise in the interior cavity due to the tire wall vibrations. The analysis is carried out by categorizing the airborne noise transfer path into the two separate consecutive events. First, the noise transfer from the vibrating tire wall to the exterior car panels is modeled by using the direct boundary element method (BEM). To this end, after discretizing the whole geometry of exterior body panels, tires, and ground into BEM models, vibro-acoustic transfer characteristics are investigated at several frequency components associated with the cavity resonances of tire. Here, cavity resonance frequencies of tire are estimated by BEM and the distribution of tire wall vibrations excited by a special vibro-acoustic source is measured at those frequencies.

Analysis of the contribution of each pass-by noise source to the overall pass-by noise is an important issue for reduction of pass-by noise. A technical approach for analyzing pass-by noise is used to identify the principal noise sources of the pass-by noise in this study. Wave propagation theory and decoupling tests are employed and the near-field measurements are carried out to obtain the characteristics of each noise source. Since the Doppler phenomenon causes a frequency shift during a pass-by noise test, the Doppler correction and time delay effects are incorporated into the estimation of pass-by noise. Combining the entire data from the action of the prior tests, a simulation program was developed for analyzing each noise source contribution and predicting the overall pass-by noise as a function of the vehicle location. Finally, the developed program can furnish an indepth understanding of the effect of each noise source to pass-by noise.