Indoor noise annoyance due to 3–5 megawatt wind turbines—An exposure–response relationship

Abstract

The existing exposure–response relationships describing the association between wind turbine sound level and noise annoyance concern turbine sizes of 0.15–3.0 MW. The main purpose of this study was to determine a relationship concerning turbines with nominal power of 3–5 MW. A cross-sectional survey was conducted around three wind power areas in Finland. The survey involved all households within a 2 km distance from the nearest turbine. Altogether, 429 households out of 753 participated. The households were exposed to wind turbine noise having sound levels within 26.7–44.2 dB LAeq. Standard prediction methods were applied to determine the sound level, LAeq, in each participant's yard. The measured sound level agreed well with the predicted sound level. The exposure–response relationship was derived between LAeq outdoors and the indoor noise annoyance. The relationship was in rather good agreement with two previous studies involving much smaller turbines (0.15–1.5 MW) under 40 dB LAeq. The Community Tolerance Level (CTL), CTL20 = 50 dB, was 3 dB lower than for two previous studies. Above 40 dB, a small number of participants prevented a reliable comparison to previous studies.