Noise
Although the noise generated by modern wind turbines is modest (compared to, for example, heavy industry or the timber industry), the rumble caused by the movement of the blades in the vicinity of a wind farm cannot be prevented entirely. Nevertheless, operating noise above normative levels from the most powerful wind turbines does not extend further than 700 metres from the turbine even under the most conservative assumptions. In any case, the developers aim to devise a wind farm that will not disturb the residents in the vicinity.
During the wind turbine design process, a noise map is drawn up, showing the estimated propagation of noise. Such noise maps are based on the assumption that all wind turbines are operating in the mode which produces the maximum amount of noise and that the noise propagates simultaneously in all directions. In real life, however, this is never the case, because noise can only travel in one direction downwind. In noise modelling, the absorption or reflection of sound on the ground is also taken into account – for example, forests are excellent noise barriers and absorb various sounds relatively well. In addition, some of the noise generated by wind turbines is attenuated by normal background noise, such as the movement of vehicles or the rustling of the wind. In conclusion, noise maps take many precautions into account, as a result of which the actual noise level is always lower than in the models.