An Excess Attenuation of the Noise Propagation over the Ground : Its estimation from Field Experiments

Abstract

Experiments were carried out to measure the noise propagation over the ground when varying the combination of heights os an artificial noise source and several receiving points. Results on excess attenuation caused when the noise propagates over the ground are mainly described. Results obtained from our experiments are as follows;1)Excess attenuation due to the noise propagation over the soft ground is rather larger in low frequencies than we expected and also influenced by the wind. 2)Excess attenuation observed is, as a whole, larger in summer than in winter. From field experiments, the empirical equation predicting excess attenuation is introduced, using non-dimensional distance coefficient as a parameter. Further we apply our empirical equation to the data measured by other researchers and show that our equation is significantly effective to predict excess attenuation caused when the noise propagates over the ground.