The acoustical performance of constructions is determined by means of standardised measuring methods based on international regulations (ISO 140) and is expressed in a single number, also according to international regulations (ISO 717). Some time ago new European standards have come into force that take care of this matter: EN-ISO 140 / 717. These new regulations have been implemented in all EU member states as their national regulations as well.

For the different types of floor constructions the acoustical performance is indicated in the following manner:

· Impact noise isolation of wooden floor constructions, measured according to NEN-EN-ISO 140-6:
Ln;w (CI), for instance Ln;w (CI) = 65 (-9)

· Improvement in the impact noise isolation of stone-like floors by means of a floor finishing or floor covering, measured according to NEN-EN-ISO 140-8:
ΔLw ; ΔLlin, for instance ΔLw ; ΔLlin = 18; 8

The frequency range for these tests ranges from 100 Hz to 2500 Hz for the ΔLlin indicator and from 315 Hz to 2500 Hz for the ΔLw indicator. For the Netherlands the ΔLlin indicator is obligatory, as this also incorporates the lower frequencies, which have the tendency to further penetrate a construction. In general, the difference between the ΔLlin and the ΔLw indicator is in general around 10 to 11 dB.