In this thesis,acoustical characteristics of a cylindrical sandwich smart shell in wich included Electrorheological or Magnetorheological fluids and immerged in an ideal fluid and was excited by a planar acoustic wave was be studied. The purpose of this study was be modelling and investigating of the acoustical properties of smart systems which included electrorheological and magnetorheological fluids.The equations of motions of the system are obtained with simultaneous implications of thin shell theory and Hamilton principal. Then, the displacement and pressure fields are deduced based on infinite series and using special vertical functions with considering to boundary conditions of the cylinder. In this study, the method of Kelvin material was be used, regarding to the natural property of this method in the implemantation of viscos damping work which make this method more physically acceptable. For the validation, a comparsion between the natural frequencies which obtained by analytical solution and those obtained by Finite Element Method was done which good agreement found between them.One of the basic important parameters in study of the response of acoustical vibration of cylindrical structures, as well as analyze of the sound transmission, is the parameter of the sound Transmission Loss which defined as the respect of the power of the inlet sound to power of transmitted sound. So,transmission loss computed regarding this definition, and then, other important physical and geometrical parameters which are effective on transmission loss such as the intensity of the electrical or magnetical fields,the incident wave angle and thickness of the core layer of smart material was be investigated in a vast domain of frequency. Also, transmission loss was calculated for a diffusive acoustic field based on a directed normal distribution by the use of Gauss weighting function.The altering of the electric or magnetic field seemed to have no appreciable effect on sound transmission loss. Furthermore, it was observed that with increasing the angle of incident wave,transmission loss increased. Changing the thickness smart layer had a broadband effect on TL over the entire range of the frequency. But the shell will have to be designed only as thick as necessary because of the weight constraint. The type of analysis developed in this work will be very useful in such a situation.The obtained results, for both of the magnetorheological and electrorheological fluids in same conditions were been compared and it was observed that the sound transmission loss was greater in magnetorheologicaal material than electrorheological material. Key Words: Cylinderical shell,Hamilton principle,Smart structures, Electrorheological camposites,Sound transmission,Sound control.