Noise reduction with a diffractor

Reducing noise with a diffractor is an entirely new way of dealing with traffic noise pollution. This type of noise reduction has been incorporated into law since January 2020. Ahead of this the diffractor has also been added to the Geomilieu software package, as one of the most suitable measures for reducing noise alongside (rail)roads.

What is a diffractor?

4Silence originally developed noise reduction through diffraction back in 2012.

Diffraction is the scientific principle that sound waves can deflect when interacting with other sounds. A diffractor is an element with grooves of varying depths. Sound waves shoot into the grooves, where they start to resonate. Sound moves like water: it looks for the path of least resistance. So the troublesome sound waves above the diffractor deflect upwards, resulting in a quieter area alongside the road.

  • A cost-effective and sustainable way to reduce noise pollution
  • Easy to install
  • Preserves views
  • Supported by residents

Three products that work with a diffractor

4Silence has translated this principle of diffraction into three products, all of them applicable in infrastructure:

WHIS®stone

This is a concrete diffractor, placed directly next to the road at ground level, realizing a 2.5 dB noise reduction, equal to silent asphalt.

WHIS®wall

The WHIS®wall combines a low noise barrier with a weathering steel diffractor. That amounts to 1 meter in height, all in all. It achieves a 7 to 9 dB noise reduction, equal to a 3 meter regular noise barrier.

WHIS®top

This is a lightweight aluminum diffractor, that can be mounted on most existing noise barriers. At only 0.2 meters in height, it’s good for a 4 to 5 dB reduction, equal to what you’d achieve by raising the barrier 2 meters.

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