In 2010 noise limits for military shooting grounds were introduced into Switzerland. In order to service a noise exposure register and to do action planning, a new calculation model for shooting sound, called sonARMS, was developed. The model will not only be used to assess military but also civil shooting ranges. It is therefore designed to reproduce single event sound exposure levels as well as maximum sound pressure levels. In a weapon database, source strength data are provided for all military weapons used in Switzerland as well as a great number of civil weapons. The sound propagation model has been derived from sonRAIL, a recently developed railway sound calculation model. It is organized into four different modules that are operated independently from each other. The first module is mandatory for each calculation as it performs a calculation of direct sound propagation including ground reflections under the assumption of a homogenous atmosphere. In the second module meteorological effects on sound propagation, most importantly the evolution of acoustical shadow zones and changes in shielding effect, are accounted for. This is achieved by applying a ray tracing procedure that can handle arbitrary gradients with height of the effective sound speed. The third and fourth module yield independent contributions, one for reflections at buildings, walls and other rigid surfaces and one for diffuse reflections at forest edges and cliffs. The algorithms in sonARMS have been optimized for minimal calculation times and allow the preparation of noise maps with a reasonable amount of computational time.
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Wunderli et al. (2012) studied this question.