Sensitivities of outdoor sound propagation predictions to environmental input parameters

Abstract

A number of reference numerical models can be used to perform outdoor sound propagation prediction in a complex environment. Most of time, either they consume little computational time by not taking all phenomena into account at the same time, or they are more complete but their calculation times are prohibitive. This paper presents some principles which can be used in reference numerical models to reduce calculation times in predicting long-range outdoor sound propagation under complex environments. Limits, assumptions and approximations used to predict outdoor sound propagation are discussed here in terms of their impact on accuracy for typical road traffic configurations as a function of frequency, geometry of the site and atmospheric conditions.

Sensitivity of CNOSSOS-EU sound propagation model to digital surface components

“…Aballéa et al investigated the sensitivity of outdoor sound propagation predictions to environmental parameters to suggest different simplified approaches which can be used to reduce the calculation time, providing results that still meet the accuracy requirements [13]. Among other parameters, the ground effect was investigated, comparing cases with various heterogeneity values of ground surface absorption to a case assuming a homogeneous equivalent ground surface.…”

“…Concerning the acoustic absorption of the ground, Kumar et al used an attribute to model the degree of noise absorption by the land area with the values of 0 (hard), 0.5 (medium/middle) and 1 (soft) [11]. In the sensitivity analysis of Aballéa et al, two types of ground (reflective and absorbing) modelled by two impedances were taken into account [13]. In the examination performed by Morley et al, the extra detailed OS MasterMap Topography Layer® (1 m precision) was used in the higher resolution test cases, while the lower resolution versions were based on the less detailed CORINE 2006v16 database (~100 m precision) [12].…”