Wind turbine sound

At first glance wind turbines seem to produce hardly any noise. During the day, at close range, one hears the blades rustling, and a soft woesh-woesh sound when a rotor blade moves downward. Close to the ground the wind velocity is relatively high. The atmosphere is called instable. Moreover other sounds are present to mask the wind turbine noise.

When the night sets in, the atmospheric conditions change and they become stable. Close to the ground the wind ‘lies down’, which leads to the expectation that a wind turbine will rotate slowly. At large, modern wind turbines the rotor is positioned at large height. At this height the wind keeps on blowing, or will even increase. With this, turbine noise increases, while there is less background sound to mask this turbine noise.

Moreover, the wind turbine sound characteristics change. Surrounding residents state that the rotor blades start ‘swishing’ or ‘lashing’. This is not a continuous sound, but it increases and decreases with the rotation of the blades. This particular characteristic might be the reason wind turbine sound is perceived as more annoying than equally strong sounds from a continuous source. Also, this characteristic makes is hard to mask wind turbine noise.