The measurement of the airborne sound insulation of building elements in sound facility suites according to ISO10140 at low frequencies is known to be problematic. Because of an insufficient number of acoustic room modes in the lower frequency range, the sound field is strongly position dependent. This lack of diffusivity causes a poor reproducibility between laboratories. This article proposes a novel approach in which mobility measurements of the building element are used to compute the airborne sound insulation R due to an ideal diffuse acoustic field. The procedure completely eliminates room acoustic effects of both the source and receiving rooms, thus allowing for a facility independent measurement of the airborne sound insulation R.
