Jim Cummings' Acoustic Ecology Institute reports have been a favourite resource of mine on the issue for some time. I think he makes some excellent points in reporting on a settlement in Michigan - one that followed shortly after a health board in Wisconsin declared an industrial wind site a public health hazard.
MI turbine suit settled; another lesson in operating too close to already-generous noise limits | aei news:
...it’s essential that enough of a safety factor is built in to the sound models to account for known variability in sound production (how loud the blades are in various unsteady wind conditions) and sound propagation (how far sound travels as it gradually loses power). Regular readers will know that variability is indeed, as Howe mentioned, often more than the simplified 3dB margin of error that was neglected here (see AEI’s 2012 report). The second half the lesson is related: when noise limits—for the sound of the turbines when it reaches nearby homes—are set as high as 45dBA, they will be regularly audible at these homes, and likely well above night-time ambient sound levels. As many acousticians have stressed for years, these situations are very apt to trigger a significant number of complaints, especially if there are dozens of homes in that nearby range. Here, we had the worst of both worlds: turbine siting plans that pushed sound right at the limit into nearby homes, and a limit that was on the high end of tolerability for many neighbors. Indeed, after one such cautionary report was presented to the Mason County Planning Board, it decided to lower the limit to 40dB, but that change was revoked after push-back from Consumers Energy.
With this backdrop, this week the 17 original plaintiffs in the noise nuisance lawsuit agreed to a settlement offer from Consumers;