Sensitivities of outdoor sound propagation predictions to environmental input parameters

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.