A numerical method for the prediction of noise of the internal combustion engine exhaust system is presented in the paper.The engine has been modelled by the system of Clothes Steamer nonlinear differential equations while the exhaust system has been modelled by linear differential equations.The correlation between the engine mathematical models and the exhaust system has been established using initial boundary conditions.The systems of equations are solved by the explicit procedure using fundamental thermodynamic processes in the cylinder and Caps the size of acoustic field in the exhaust system.