The change of a vortex-shedding characteristics causes changes in the Strouhal number, characteristics length, and acoustic pressure. It is known that the major parameters to predict the acoustic pressure are the flow velocity, the characteristic length, and the fluctuating lift coefficient. In this paper, numerical analysis of the flow field and acoustic analogy are utilized to predict the noise field about a circular cylinder by using CAA(Computational Aeroacoustics) method of a commercial code, Fluent, and the results are compared to the available experimental data.