How loud is a wind turbine?

A lot is made about the noise of wind turbines. Camping right underneath one at Kessingland in Suffolk gave me the chance to experience it for myself. It is a constant background when the wind is blowing and as such I was able to zone out in the night. The traffic on the main road 2 fields away was more intrusive. I would say that it wasn't as loud as the sea at Rhossili campsite. The traffic noise in the middle of a city is definitely worse but then they don't put turbines in those sorts of places. It has made me resolve to see if I can find a sound meter to bring away with me to put a number to these noises!