Sound Insulation in Buildings and of building Elements BS EN ISO 140-7:1998:

The method for measuring the field sound insulation of building elements is given in BS EN ISO 140-4:1998 and an additional method for measuring the impact sound insulation for floors is given in BS EN ISO 140-7:1998. Once the sound reduction index has been measured the result can be rated to give single number figures and adaptation terms in accordance with BS EN ISO 717.

Local authorities now require compliance with these standards for planning approval and sign off of building projects.