This work presents a method to determine mechanical transfer functions from forces, acting on the stator teeth of an electrical machine, to surface velocities at sound radiating surfaces. The method allows an efficient analysis of drive trains in their target application and real environment. The determined transfer functions are used in a transient acoustic model for the simulation of electrical drive trains. The proposed model takes care of the nonlinear power electronics, the digital control and sensors, as well as of tolerance afflicted geometries of electrical machines and real and in tolerance deviating material properties. The model is validated by means of vibration measurements. The benefits of a closed simulation in time domain are declared. Exemplary applications of the proposed model are discussed and the potential of the acoustic evaluation during the design process of an electrical machine is illustrated.