This to a large extent depends on the type of usage of the premises. As a general rule most identifiable sound is transferred through cross walls and most sound transmission through cross walls, suspended ceilings, raised floors and doors. Requirements for levels or airborne sound resistance have steadily increased in recent years which is reflected in the majority of specifications for standard offices to be 40Rw(dB) or more for all partition walls. Acoustic ratings on partitions are conducted in laboratory conditions which cannot be reproduced on
site, therefore, a loss of up to 10% on the tested figure is to be expected when the system is installed. Best results are obtained when the system is fitted slab to slab.