A Model for Diffracting Elements to Reduce Traffic Noise

Invited paper

Ysbrand Wijnant

University of Twente

Tuesday 2 june, 2015, 13:40 - 14:00

0.2 Berlin (90)

In the Netherlands there is a great demand for noise reducing measures to fulfill the noise legislation and to reduce the annoyance of traffic noise. Silent pavements and noise barriers are well-known, but are there other alternative or additional measures? The company 4Silence developed a sound diffracting element (Whisstone); a concrete element with cavities that is placed alongside the road at the same level as the road surface. The diffracting element deflects tyre-road noise in an upward direction, creating a zone of noise reduction behind the element. It can therefore act as a complement to existing noise-reducing measures and can be optimized for maximum noise reduction. Based on a finite element model, it is possible to assess the performance of the diffracting elements. However, these models are impractically large to optimize the geometry for maximum sound reduction. We therefore developed a very fast, semi-numerical model, which makes optimization of the geometry feasible. In this paper we present this semi-numerical model and report the validation of its correctness by comparison with a finite element model. In an accompanying paper of J. Hooghwerff, a measurement setup and actual experimental results for the diffracting elements will be presented, showing that this innovation can increase noise reduction up to 4 dB.

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