With the development of computer simulation technique for room acoustics, diffuse reflection is considered more and more important. In this paper, some models are developed by considering two diffuse factors in a room|diffuse reflection due to room surfaces and scattering due to objects. The surface diffusion is treated by two different methods on the basis of probability analysis or Energy Conservation Law, and the scattering among objects is simulated as a multiple random ray|tracing process. Thus the sound pressure level distribution in a diffuse sound field can be calculated more precisely and easily. Agreement between the computer simulation results and measurements shows the accuracy of the mathematical and physical model and the applicability of the computer simulation methods. These models can be used in noise control engineering, as well as in the practice of acoustical design. Diffuse reflection of is room materials and scattering due to . The surface diffusion is treated by two different methods on the basis of probability analysis or Energy Conservation Law, and the scattering among objects is simulated as a multiple random ray|tracing process. Thus the sound pressure level distribution in a diffuse sound field Can be calculated more precisely and easily. Agreement between the computer simulation results and measurements shows the accuracy of the mathematical and physical model and the applicability of the computer simulation methods. These models can be used in noise control engineering, as well as in the practice. Of acoustical design.