Sweden is now considering new railway lines typically adapted to high speeds up to 320 km/h. Noise impact from high-speed lines andnoise mitigation measures where required becomes urgent to be investigated. As the current calculation model for railway noise used in Sweden isnot applicable for the purpose, the Swedish Transport Administration decides to prepare a new noiseassessment method for high-speed lines. This new noise assessment method is not necessary to be comprehensive because noise evaluation a long high-speed lines is mainly oriented. In this paper a simplified sourcemodule is described. The simplification has threefolds of meanings: (1) only dominant noise sources, rolling noise and aerodynamic noise, are considered; (2) aclassification of train types is made based on noise emission strength, not on the physical parameters; (3) the effectof noise measures (such as rail/wheel dampers, sleeper pads or mats, wheel skirts, etc.) isintegrated into a single parameter, additional noise reduction (given either in total level or in spectrum). Moreover, the effect of noise barriersalong a high-speed line is left to be handled by the sound propagation module.