Contains a basic calculation of the resulting reduction in level difference across a separating element as a result of noise travelling through the ductwork serving the adjacent rooms. First the level difference arising from noise in the source room reverberant field travelling though the ductwork and being received in the receive room is calculated. Then the level difference arising from noise travelling through the partition is calculated. Finally, the two are added to determine the resultant level difference. This calculation only takes account of noise in the reverberant field in the source room, which is assumed to be diffuse -i.e. there is no direct component taken into account. Noise sources giving rise to a direct component (e.g. specific sources giving rise to a significant direct component at the entrance grille) would need special consideration. Similarly, there is no direct component through the partition, however the direct field radiated from the separating element is taken into account. This calculation has been developed from a review of available calcs from various sources, so ensure you are happy with the methodology before using.