An automatic and fast numerical coupling method between 2-D electromagnetic and 3-D structural FEM software is presented. The described coupling method permits to compute the electromagnetic noise in electric machines for different realistic alimentation currents. Thanks to this tool, the strong influence of the supply harmonics on the acoustic level of a synchronous machine is clearly shown. This method has been developed for a wound rotor synchronous machine (WRSM) but can be applied for any non-skewed machines. First of all, the global principle of the study and the magnetic noise theory is briefly introduced. Then, computation algorithms coupling magnetic forces to structural mesh are developed and finally simulation results show the influence of supply harmonics on global vibration levels.