[Drdrdrq]

It is also possible that they generate the sound of the same frequency, but coming from multiple sources it can compound in some areas to be louder than elsewhere - and those areas could change with the direction of the wind.

This is purely speculation from my side of course, as I've never been there.

[DagAgren]

No, it's a pretty safe bet that any of these complaints about wind turbines is just NIMBYism. It happens every single time.