FDTD method and CIP method are used for an acoustic analysis in time domain. However, these methods do not take into account a sound attenuation from viscosity. In our study, we propose a concentrated mass model which consists of spring-mass-damper system to perform a two-dimensional acoustic analysis. The dampers of this model consider viscosity of air. In this paper, we derive mass, connecting springs, connecting dampers, and base support dampers. The characteristic of the connecting spring is derived from the condition of adiabatic change of air, and the connecting damper is derived from the normal stress. To confirm the validity of the proposed model, the numerical results obtained by the concentrated mass model are compared with the theoretical value of the traveling wave, and with the theoretical value of the natural frequency. All numerical computational results agree very well with the theoretical values. Therefore, it is concluded that the proposed model is valid for the two-dimensional acoustic analysis.