Military systems powered by internal combustion engines emit noise from the exhaust system. There are two types of noise, airborne, due to the pressure wave propagating through the exhaust system and exiting at the outlet and structure - borne, radiated from the vibrating components of the exhaust system. The objective of this project is to develop a computer code simulating the exhaust system, and predicting accurately both structure - borne and airborne noise. An elasto-acoustic model will be developed and implemented in computer code. The effects of mean flow, temperature gradient, and multi-dimensionality will be accounted for in the model. Experimental measurements from an exhaust system will be used to validate the code. The developed software will be a valuable tool in designing exhaust systems with improved noise characteristics. It will allow the study of different configurations without actually constructing and testing them. This will increase the effectiveness in designing exhaust systems. In the future, this software can be incorporated into noise control technologies for designing improved exhaust systems. Active noise control, adaptive exhaust system design, and muffler shape optimization, are areas where the developed software can be applied.