Wind farms have their own set of noise regulations (ETSU-R-97) to adhere to, because they would not pass the usual BS4142 standard that all other developments have to meet.
The ETSU regulations are outdated and widely discredited. They were written (partly by the wind industry itself) 15 years ago and based on much smaller turbines than are now the norm. ETSU incorrectly calculates wind shear and ignores the acoustic effects of wind turbine noise. A review was promised 12 years ago, but we’re still waiting. This is a very technical but important article prepared for possible presentation to DECC: ‘Bad Science’ behind wind turbine noise regulations.
Noise from a wind turbine can be heard within 2km of the source. It includes tonal noise (air flow whistling over the blades), broadband noise (whooshing) and impulsive noise (as disturbed air interacts between the blades and tower). Unlike traffic noise which occurs at ground level, wind turbine noise cannot be ‘screened’ in any way.
There is lots of very useful info about wind farm noise on this site.
Noise is the issue which causes most of the health concerns relating to wind turbines.