ESDU 82003 illustrates, by means of a worked example, the application of data provided in ESDU 79037, 81043, 82001 and 82002. These provide the essential data for the estimation of sound pressure levels resulting from the operation of a ducted ventilation system within a room served by that system. The example calculation considers a typical office ventilation system and discusses possible ways of reducing the flow generated noise in order to meet the noise design criteria. The data are intended for use by engineers who are not acoustic specialists.