The Environmental Noise Directive (2002/49/EC) requires EU Member States to determine the exposure to environmental noise through strategic noise mapping and to elaborate action plans in order to reduce noise pollution, where necessary. A common framework for noise assessment methods (CNOSSOS-EU) has been developed by the European Commission in co-operation with the EU Member States to be applied for strategic noise mapping as required by the Environment Noise Directive (2002/49/EC). CNOSSOS-EU represents a harmonised and coherent approach to assess noise levels from the main sources of noise (road traffic, railway traffic, aircraft and industrial) across Europe. This paper outlines the process behind the development of CNOSSOS-EU and the parts of the CNOSSOS-EU core methodological framework which were developed during phase A of the CNOSSOS-EU process (2010-2012), whilst focusing on the main scientific and technical issues that were addressed, and the implementation challenges that are being faced before it can become fully operational in the EU MS.
A geometrical cone-tracing method associated with the signal processing technique is used to calculate the binaural impulse response of a concert hall. Some inaccuracy and the computation time of the geometrical algorithm tend to limit the method for the high-reflection orders which are necessary to provide a good listening effect. In order to extend the response, a new approach is presented based on different statistical processes that depend on both the acoustical and geometrical characteristics of the hall. After a theoretical presentation (new statistical results are proposed to describe the sound field behavior in a concert hall), some simulations are given in order to illustrate the different statistical processes. This simulation technique seems to be a very convenient tool both for the design of a new concert hall and for the study of the important parameters in auditory spaciousness.
Modeling outdoor sound propagation in cities is challenging because they often have complicated geometries and large domain sizes. One hybrid approach uses an engineering method (e.g., Harmonoise or Nord2000) with an extra attenuation term for interactions with complicated geometries like a T-barrier. The extra term quantifies the additional attenuation from the complex geometry compared to a reference geometry that can be modeled in the engineering method. Calculating pressure levels using a detailed method such as the Boundary Element Method (BEM) for the complex and reference geometries over multiple source and receiver positions and frequencies yields a table of excess attenuations. Interpolating this table of corrections at the desired source/receiver location and frequency produces the desired relative attenuation. This presentation discusses the development of this method for a case that has multiple propagation paths due to reflections from buildings and one interaction with a complex geometry per path but no additional diffraction points. The hybrid method agrees well with 3D BEM calculations at low frequencies.
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