Airborne sound insulation is denoted:
Rw = weighted sound reduction as measured in laboratory
R'w = weighted sound reduction index measured in buildings
Laboratory measurements will typically be 4-5 dB better than measurements made in buildings for the same construction.
Sound reduction (explanation):
A chance, which is accurately that big that it can be recognized.
An appreciable change, which is clearly to hear.
-corresponding to a change of the hearing impression of 20%
-corresponding to theoretically halving of the sound pressure.
A significant change, which is very clearly to hear.
-corresponding to a change of the hearing impression of 35%
A very significant change, which man perceives as a halving of the sound.
-corresponding to a change of the hearing impression of 50%.
The sound reduction for example achieved through a plate-lined wall depends on several factors:
1. The sonic properties of the plate lining.
2. The distance between the plates.
3. Whether there is contact between the plates for example through uprights, or if the plates stand independently.
4. Whether the cavity is uninsulated or if it is insulated with for example 100 kg Bonded Foam (RE100).