the human ear can hear noise from 20-20,000 Hertz (Hz). Low-frequency is found at 20-200 Hz, and below 20 Hz is infrasound
A great excerpt from owensoundsuntimes explaining wind turbine noise:
In Germany, if a wind farm is built in an environment characterized by a 35 DB ambient noise level the setback from any receptor is 1.5 kilometres.
Unfortunately, all of this only focuses on part of the issue of environmental noise. That is, that part of the noise spectrum that humans can hear. The other part is the noise that is less audible or completely inaudible such as low frequency noise and infrasound. What we know from scientific research is that low frequency noise and infrasound behaves differently from higher frequency audible sounds in that it does not decrease over distances. That partially explains why elephants and whales use low frequency noise to communicate over great distances through the ground and oceans.
We also understand that solid structures like houses can actually amplify the sound through vibration. That means it won’t be blocked out by going inside and shutting doors and windows. Only a portion of low frequency noise is audible. Infrasound, defined as less than 20 Hz, is below the hearing threshold of humans. It will only be felt through inner ears and body sensations. Thus the volume in decibels is irrelevant because you don’t hear it. Increased volumes of infrasound will however, speed the body reaction.
What we know from science is that every organ in the human body can resonate or vibrate from exposure to low frequency noise. As examples; low frequency noise of 50 Hz (hertz) stimulates vibration in the chest cavity; at 30 Hz abdominal organs can do the same; at 17 Hz vision can be blurred due to vibration of optic nerves. The science concerning the risk of exposure for humans is explicit. It has been acquired from years of occupational studies, military experiments and the life experience of individuals in neighbourhoods co-located with industrial factories.
This can also be found on pages 44-45 of the book Dirty Business