Abstract
Long-term measurements of sound from wind turbines show variations of the order of 6 - 14 dBA at some distance from the source. The meteorological conditions change over the day and the year and vary a lot depending of the terrain conditions. The meteorological parameters govern both the wind turbine sound level and the sound propagation conditions. In an extensive measurement program, with economical support from the Swedish Energy Agency, long-time measurements of meteorological effects on sound propagation from wind turbines are performed at three sites in Sweden. The measurements are performed during 1-2 years. Sound propagation is studied in a 1) forest area, 2) over a water bay and 3) over heterogeneous terrain. The first two sites are located in the southern part of Sweden and the third is located in the northern part of Sweden. The aim of the project is to improve the knowledge about sound propagation from wind turbines and especially over varying terrain and different weather conditions. The hub height of the studied wind turbines varies from 80 - 138 m. The result shall be improved sound propagation models, updated measuring requirements, validation of modeled sound levels and methods for deriving meteorological input data for a sound propagation model. In this paper preliminary results from the first 10 months are presented.
