The WHIS®top is a lightweight aluminum diffractor that can be mounted on existing (or new) noise barriers to deflect sound upwards, resulting in a noise reduction of 4 to 5 dB. This is equivalent to raising the existing noise barrier by 2 meters, but without the visual impact of a taller structure. In Venlo, Annakamp, a total of 140 meters of WHIS®top has been installed.
