The present status of a method to calculate the generation, transmission and radiation of fan noise is described. A steady uniform flow is assumed in the whole field. A hard-walled circular duct is considered which is terminated at the open end by an infinite baffle. The source mechanism is the impingement of wakes from an upstream blade row giving rise to fluctuating bldde forces. This force field drives the sound field. The method is illustrated by means of numerical examples.