The Effect of Foundation Details and Soil Types on the Airborne Sound Insulation of Masonry Cavity Walls

Two important variables that affect the airborne sound insulation of cavity masonry separating walls in the field are the foundation detail and the soil type upon which the foundations are built. Vibration transmission was measured between cavity wall leaves on three different types of foundation: concrete deep trench fill, a strip footing and a strip footing with concrete infill. The results indicated that where a strip footing is used, higher sound insulation can be achieved without the concrete infill. Measurements of the dynamic properties of soils indicated significant differences between the compression stiffness per unit area and the loss factor of different soils. These different soil properties were seen to affect the airborne sound insulation of cavity walls. This explains some of the variation in airborne sound insulation between nominally identical masonry cavity separating walls in the field.