A readily available method for predicting the noise propagated from an
agricultural enterprise to the farm boundary would enable this noise
to be more easily reduced. This paper reviews the theory and practice
of outdoor sound propagation modelling. The contributions of geometric
divergence, atmospheric absorption, barriers, the ground effect and m
eteorological conditions are described. Theoretical models and empiric
al schemes for predicting noise propagation are considered. The import
ance of the ground effect indicates potential for reducing environment
al noise through farmland management. Current limitations on the abili
ty to predict noise propagated over farm land are owing to a lack of k
nowledge about the characteristics of typical field surfaces, difficul
ty in modelling some typical meterological conditions and the long com
putation times required.