Is ILFN the Smoking Gun?
Two recent essays highlight aspects of wind turbine impacts, addressing effects that go beyond audible noise. Both are written by distinguished experts who have the research background needed to comment authoritatively about infrasound.
In How does wind turbine noise affect people? researchers Alec Salt and Jeffrey Lichtenhan point out the physiological mechanisms their studies have uncovered. These contribute to the growing body of evidence that noise from wind turbines, even that below the audible threshold, can impact humans who live near turbines. Acoustics Today published this invited paper in the Winter 2014 issue in March 2014. This magazine of the Acoustical Society of America exists to present technical issues in a form accessible to a general audience. In this article Salt and Lichtenhan explain the recent progress in understanding the ear and its responses to infrasound and low frequency noise. They answer those who dismiss the effect of infrasound on the ear and on other body systems:
The current highly-polarized situation has arisen because our understanding of the consequences of long-term infrasound stimulation remains at a very primitive level. Based on well-established principles of the physiology of the ear and how it responds to very low frequency sounds, there is ample justification to take this problem more seriously than it has been to date.
In Wind Farms and Health, Alun Evans, a medical doctor, epidemiologist and researcher, analyzes the biology of wind turbine emissions in the context of his specialty. Drawing the inferences of disturbed sleep from recent studies, and the rapidity with which the body produces genetic anomalies in blood cells based on lack of sleep, Evans sounds the alarm. Study after study that he cites note problems and impacts that have been ignored or dismissed.
Although the associations between noise pollution and ill health can be argued against, and there are gaps in our knowledge, there is sufficient evidence to cause grave misgivings about its safety.
Wind Wise ~ Massachusetts 
Most of the sound studies of wind farms by owners and state agencies have used dBA weighted data. This suppresses infrasound by 60-70 dB so it’s not surprising they trigger existing standards. Studies with unweighted (or even dBC weighting) show infrasound increases in power down to 1 Hz or so.
1.25 mile setbacks are not enough for infrasound output of 2 MW or greater turbines.
Your points about audible sound are good and worthwhile pursuing while also trying to get some sensible standards for infrasound.
I feel compelled to warn everyone that there is a serious problem associated with claims that ILFN is the Smoking Gun in the search for the ill health associated with wind turbine sound emissions.
It is not that these studies are wrong. They may be exactly true. However, all the infrasound measurements of wind turbine emissions have not found ILFN at levels that are recognized by existing standards as dangerous.
On the other hand, A weighted sound levels in Falmouth, Fairhaven, Kingston and elsewhere have been measured at more than twice the state legal limit, and more than 10 dBA above the limits set by the World Health Organization (WHO).
Without denying the existence of ILFN and its effect on health, it is much easier to get physical evidence that A-weighted noise pollution levels must be reduced. Reducing A-weighted sound to safe levels can only be done by establishing a mile and a quarter setback from the nearest turbine.
I believe and hope that a 1.25 mile setback will not only avoid A-weighted sound, but it will also eliminate the ill-effects of ILFN identified in these studies.