ABSTRACT
In many situations, for example where plant or equipment already exists, it may not be feasible to modify the characteristics of the noise source. In these cases, a possible solution to a noise problem is to modify the acoustic transmission path or paths between the source of the noise and the listener. In such a situation the first task for noise-control purposes, is to determine the transmission paths and order them in relative importance. For example, on close inspection it may transpire that, although the source of noise is readily identified, the important acoustic radiation originates elsewhere, from structures mechanically connected to the source. In this case structure-borne sound is more important than the airborne component. In considering enclosures for noise control one must always guard against such a possibility; if structure-borne sound is the problem, an enclosure to contain airborne sound can be completely useless.
