To research the mechanism of automobile aerodynamic noise which transmits to the inside of a cabin, flow structure and sound field have been investigated by applying experimental measurements at the wind tunnel and computational fluid dynamics (CFD) based on lattice Boltzmann method (LBM). In this research, transmitted noise at a front side window glass is focused. Pressure fluctuations on the side window glass contain both hydrodynamic pressure fluctuations induced by convection of flow field and acoustic pressure fluctuations propagated from noise sources. But it was found that acoustic pressure fluctuations have large contributions on the side window glass at the high frequency range by considering of the experimental transmission loss. On the other hand, at the low frequency range, hydrodynamic pressure fluctuations are dominant, however their effects to transmitted noise are not so influential for high fluctuation levels.