Effects of meteorological conditions and source height on sound propagation near the ground

Abstract

Simultaneous measurements of sound propagation from a loudspeaker and meteorological variables were carried out for various ground covers and meteorological conditions. The wind and temperature gradients cause refraction of the sound rays, and hence influence the sound level. The curvature of a nearly horizontal sound ray can be calculated by using measurements of wind and temperature. The curvature is found to be closely connected to the sound level, when distinctions between octave band, ground, distance, source and receiver heights are made. A new variable, the sound propagation parameter, W, including refraction, distance, source and receiver heights, is introduced. The parameter is used to examine if a specific set-up of source-receiver can be sensitive to meteorological effects. The sound level for different octave bands and ground cover is given for negative and positive values of W, outside an interval close to W = 0, where large scattering of the sound level is found.