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Calculating traffic noise reduction at long distance using diffracting elements

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Author: Brouns, E. · Eerden, F. van der · Eisses, A.R. · Kruyen, A.H.J. · Vliet, W. van
Type:article
Date:2018
Publisher: Institute of Noise Control Engineering
Source:INTER-NOISE 2018 - 47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering, 47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering, INTER-NOISE 2018, 26 August 2018 through 29 August 2018
Identifier: 858045
Keywords: Noise abatement · Noise pollution · Numerical methods · Resonators · Broad frequency range · Calculation models · Meteorological effects · National standard · Numerical results · Octave bands · Parabolic equation method · Acoustic variables control

Abstract

A series of resonators alongside a road or railway can be used to diffract noise upwards to create a zone of noise reduction behind the elements. The company 4Silence developed the so-called Whisstone, a concrete block with 18 resonators of different depths designed to operate in a broad frequency range. Several measurements at short distance, up to 15 meters, have proven that a noise reduction up to 4 dB(A) can be achieved. To determine the noise reduction at long distances calculations are necessary, due to the uncertainties of ground and meteorological effects. In this paper a comparison between measurements and numerical results (FEM) at short distance is presented. The positive results of this comparison allow the numerical method to be applied at larger ranges, up to 600 meters, taking a downwind condition into account. To this end the FEM method is coupled to a Green's function parabolic equation method (GFPE). The calculations for long distances show noise reductions up to 5 dB in octave bands and 3 dB(A) for the broadband level. These results can be used to account for the diffracting elements in standard noise calculation models used in practice, such as the Dutch national standard model or Cnossos. © INTER-NOISE 2018 - 47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering. All rights reserved.