This paper deals with the problem of sound propagation in urban areas, a real tool leading to smart cities design. It begins by studying the propagation of sound in order to determine and extract the physical parameters that direct this propagation. Then it deals with the formalism of cellular automata and their relation to the specification of physical phenomena with discrete events, such as sound propagation. Then, this technique (cellular automata) is used in a smart city context, to model the propagation of sound, taking into account buildings and other various city obstacles. An implementation is made in CUDA, to simulate this phenomenon on shapefile cards. This work ends with the determination of the sound power in a given location and the geographic area covered by the sound wave.