Wind turbines and noise
The Noise from wind turbines is similar to other types of noise in our day-to-day environment, such as a household refrigerator. The type of sound produced by a large wind turbine is primarily aerodynamic.
Despite the presence of a generator (and usually a gearbox) in the nacelle, the noise produced from these internal mechanical parts is generally inaudible. The sound that is developed comes from the movement of the wind over the rotating blades. This 'swooshing' noise varies in intensity as the blades rotate. Because the wind speed is usually higher at the top of the rotor than the bottom, as the blades turn there is a constant variation in sound intensity.
Most people perceive this aerodynamic sound as more natural than "industrial noise" and some have described it as a little like the sound of breaking waves on a beach.
When the position of wind turbines is being planned, extensive design work is undertaken to minimize noise impact on residents. A sizable buffer zone is established between turbines and residents and the way in which sound travels over the landscape is modeled. To assist in detailed planning, actual on-site SPL measurements are made of background noise.