Instructions for processing of near field reflectivity test data and derivation of far field reflectivity indicators
Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk Onderzoek
de Roo, F.
Sound reflectivity is one of the intrinsic acoustical characteristics of noise reducing devices (NRD’s). It describes which percentage of an incident sound field is reflected back towards the opposite side of the road. The reflectivity is determined by the absorption properties of the material of the NRD as well as by the geometrical shape of the NRD, which may enhance or reduce sound reflections in particular directions. The reflectivity effect in the far field is thus not only related to the NRD and its design, but also to the receiving position in the far field. The main task of QUIESST Work Package 2 was to develop an engineering method for the extrapolation of the results of the near field reflectivity test developed in WP 3 to estimate the contribution of reflected sound to the sound levels in the far field of a NRD. In the Final report of WP 2 all development steps to achieve the intended engineering method are described in detail. The final result of WP 2 is an engineering computation method that gives the values of two far field reflectivity performance indicators (for High-rise and Low-rise buildings) for a particular NRD type. In this deliverable the characteristics of the engineering extrapolation method are described and instructions for use of the method are given. The format of this description is that of an Annex to a European Standard. This format is used with the intention that the engineering extrapolation method shall be used in conjunction with the revised near field reflectivity test method developed in WP 3. This test method is intended to replace the method in the current European Standard EN 1793-5:2002 and the engineering extrapolation method may then be added to the revised standard as an Annex. For an easy use of the engineering extrapolation method it is implemented in a pre-programmed Excel spread sheet. The spread sheet will be published together with this present report and can be downloaded from the QUIESST website (www.quiesst.eu). It may also be distributed together with the revised version of EN 1793-5.
Acoustics and Audiology
To reference this document use:
Buildings and Infrastructure
Physics & Electronics
AS - Acoustics & Sonar
TS - Technical Sciences
FP7-SST-2008-RTD-1, Seventh Framework Programme, Theme 7: Transport, WP 2 – Relationship near-field/far-field for sound reflection. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n°SCP8-GA-2009-233730.