Elemental normalized level difference

Professional Definition

The standardized equivalent level difference (Dn,e) is a parameter that defines the acoustic insulation of building elements with an area smaller than 1 m2, such as window vents, ventilation grilles, or installation ducts.

This indicator refers to the equivalent absorption area in the receiving room. Unlike standard specific insulation (R), for Dn,e we do not divide the result by the area of the element itself. This is because, for very small components, their physical surface is often ambiguous or negligible in relation to the entire wall, while the total sound energy flow that penetrates through them is crucial.

Acoustics in Simple Words

Imagine that your room is a sealed aquarium, and sound is water trying to pour in:

• If you have a large hole in the window (for example, with an area of one square meter), you use a standard measure of insulation to describe the leak.

• But what if you installed a small pipe (equivalent to a vent) in the wall of the aquarium?

The standardized equivalent level difference is the label attached to that specific pipe. It says:

"No matter how big the wall is that I am installed in – I will let through exactly the same amount of noise".

This is like assessing the tightness of a specific model of a faucet rather than the entire plumbing system. Thanks to this measure, architects know whether a given model of vent will not "disturb" the peace in an apartment, becoming a weak point in an otherwise perfect wall.

Summary

• Application: The Dn,e parameter is used to assess small elements (below 1 m2).

• Precision: It helps avoid the creation of so-called acoustic bridges – spots through which noise "escapes" inside despite thick walls.

• Practice: Essential when selecting vents, ventilation grilles, and any ducts for pipes or cables.