Weighted indicator of equivalent sound insulation (R'w)

Professional Definition

The weighted indicative of the effective acoustic insulation (R'w) is a single-number parameter that defines the acoustic insulation of a partition under real conditions (in situ), taking into account the lateral transmission of sound.

Unlike the laboratory Rw, the indicator R'w is determined based on field measurements. It accounts not only for the energy penetrating directly through the tested wall but also for the energy transmitted through side paths (floors, adjacent walls, ventilation ducts). Typically, R'w is lower than Rw by several decibels, depending on the quality of workmanship and the construction of building joints.

Acoustics in Simple Words

Imagine an aquarium. The laboratory indicator (Rw) pertains to the glass itself – how airtight it is. The approximate indicator (R'w) assesses the airtightness of that aquarium when it is already embedded in the wall, connected to pipes, and sitting on a cabinet.

Even if the glass is armored, water (sound) can leak through seals, pipes, or joints with the floor. R'w is that real result that tells us how much noise will actually be retained in the finished building, taking into account all the acoustic "leaks" in the construction.

Summary

The R'w indicator is crucial during acoustic inspections of buildings and verification of compliance with building standards. It is this indicator, not the catalog Rw, that determines the actual acoustic comfort of the residents.