Railroad noise affected by downward refraction and turbulence

For downward ray bending (temperature inversion and/or
downwind propagation) geometrical spreading is principally affected by
atmospheric turbulence. Additionally, the variations of rolling stock and train
speed occur. Thus, the sound exposure level, LAE, changes from train to train
and the equivalent continuous A-weighted sound pressure level of railroad noise,
LAeqT, changes from day to day. As such, the mean, LAeqT, is important
environmental noise characteristics. The simplified model of noise generation
and propagation is derived. It makes possible to calculate LAeqT. Two adjustable
parameters of the model are estimated from measurements of the sound exposure
level, LAE.