What is the difference between ΔLlin and ΔLw?Floor Marcus
When you buy a (sub) floor you often see the terms Δ(delta)Lw and Δ(delta)Llin on the packaging or technical data sheet. But what is the difference between these two terms?
In the Netherlands (and Belgium/France) we usually use Delta Llin. The value associated with this is based mainly on low tones. In contrast, the value of Delta Lw is based on medium and high tones. For example, these values are often used in the DACH countries and Italy. In Europe we use one measurement from which two numbers come, the Δ(delta)Lw and Δ(delta)Llin.
The ΔLw value is usually much higher than the ΔLin value but the ΔLin value (always referred to in the Netherlands as the minimal required reduction) is ΔLin = 10 dB. To explain the difference, we have to go back to the basics.
A sound can be described by its composition of various frequencies and sound levels. Its frequency is expressed in Hz (Hertz) and its sound level is expressed in dB (decibel). Also used is the Δ, the symbol for delta. This expresses the improvement in contact noise resulting from the contact noise insulation provided by a floor finish or floor covering as measured according to NEN-EN-IS0 140-8. In fact, this is the difference between the bare test floor and the test floor after installing the floor covering elements (the underlay plus the floor covering).