In a recent article about the Kingston turbine a home owner described it like a jet flying over their home. However, based upon my visits to turbines in Hull MA I would describe the predominant sound as a gentle soothing swoosh sound and it is pretty hard to hear unless you are really close. More recently I visited the Kingston turbine to hear for myself you can see it here on Google Earth 41.978808°, -70.715810°. Standing about 100 yards from the turbine I was truly astonished, initially I could not hear anything but the nearby traffic. Then as I listened more closely I was able to hear a light humming of the equipment.
The people in Kingston complaining chose to live next to Rte. 3, a high speed, divided limited access highway. The highway is between them and the turbine. If that doesn’t keep them up at night it is unimaginable that the sound of the turbine would. Here is a Globe article that gives a flavor of the whole thing.
I ran across this graphic that is quite good for putting it in perspective. While this is put out by GE ( a turbine mfg.), it is consistent with other similar graphics I have seen. http://i2.wp.com/cleantechnica.com/files/2011/12/wind-noise-chart-11-2910z.jpg?resize=570%2C398
Here is a more detailed post on the Kingston turbine and siting issues in general. It includes links to papers on the health effects of turbines. And here is a link to a well researched blog that examines many of the issues concerning wind and wind turbine siting.