Weighted normalized impact level indicator

Professional Definition

The weighted normalized impact level is the impact level specified in the standard frequency range, reduced to a single value according to the method specified in the standard PN-EN ISO 717-2. It is denoted by the letter "w" in the index of the given parameter symbol.

In engineering practice, this parameter (most often denoted as L'n,w) is used to assess the acoustic insulation of floors from impact sounds (e.g., footsteps, falling objects). It is a single numerical value obtained by applying a reference curve to the measurement results in third-octave bands. Crucially: the lower the value of this indicator, the better the insulation of the floor and the less noise transmitted to the room below.

Acoustics in Simple Words

Imagine that the insulation of your ceiling is a score in golf – the fewer points you accumulate, the better you play. Rough acoustic measurements are a complicated graph that is hard to quickly compare. The weighted indicator acts like a judge who looks at this graph and gives one specific rating (e.g., 55 dB). This way, the architect does not need to analyze the entire frequency spectrum, just looks at one number: if the ceiling has 50 dB, it is quieter (better) than one that has 60 dB.

Summary

The weighted normalized impact level is a fundamental parameter for verifying buildings' compliance with noise standards. It allows reducing the complicated physics of floor vibrations to a single value, facilitating the design of quiet apartments.