noise propagation

modulation of noise amplitude

noise level fluctuations

wind turbine

noise measurements

noise character

Industrial noise control

Wind energy

The aim of this study was to assess the discrepancies of the results of equivalent sound levels measured locally in relation to changes in acoustic pressure. The article studies both single turbines and wind farms, where fluctuations in acoustic pressure are clearly audible. The object of this study was turbines in northwestern and central Poland, which were studied either as single objects or as a group (several turbines together in one wind farm). Presented results of measurements were selected in terms of significant disturbances. Despite this process, it was impossible to eliminate the influence of gusts of wind that showed up in almost all graphs, especially in measurement points of 500 m distance from the edge of a turbine tower. It was noticed that during sound emissions not all turbines show significant fluctuation of acoustic pressure levels. It was pointed out that equivalent sound level L_AeqT – which in most countries is the indicator of acoustic climate assessment – forms the above statistical average L_A50 calculated from the measurement of acoustic pressure level SPL and regards the changeability of acoustic pressure levels in time.