Kelley, ND 1987, Problem with Low Frequency Noise-Wind Turbines Scientifically Identified
A proposed metric for assessing the potential of community annoyance from wind turbine low-frequency noise emissions
N.D. Kelley, Solar Energy Research Institute, Colorado 1987
In research supported by the U.S. Department of Energy, Dr Neil Kelley and his colleagues previously identified impulsive low frequency noise, infrasound and vibration from wind energy projects as producing ‘annoyance’ within neighbours’ homes.
This important subsequent Laboratory research confirming the direct causation of annoyance symptoms in volunteers exposed to infrasound and low frequency noise in a custom made laboratory was presented by Dr Neil Kelley at the American Wind Energy Association Conference in 1987.
This research paper clearly identifies the direct causal link between impulsive infrasound and low frequency noise, generated in the laboratory study, and “annoyance” symptoms in volunteers.
As a result of the body of research led by Dr Neil Kelley, including this laboratory study and the field research investigating impulsive gas turbine noise and wind turbine noise in 1982 and 1985, the design of wind turbines was altered from downwind bladed to upwind bladed horizontal axis wind turbines, in order to reduce the generation of excessive levels of infrasound and low frequency noise, which Kelley et al clearly established were causing sleep deprivation and other “annoyance” symptoms, known to be harmful to health.
Whilst it was initially thought that the new upwind bladed horizontal axis wind turbines did not generate high levels of infrasound and low frequency noise, NASA research published by Shepherd and Hubbard only 2 years later in 1989 established that where there was turbulent air feeding into the upwind bladed wind turbines they could generate surprisingly high levels of infrasound and low frequency noise.
Two questions arise:
1. Why is the knowledge of a direct causal link between impulsive infrasound and low frequency noise and “annoyance” symptoms still denied by anyone, but particularly by the wind industry and government regulatory and health authorities?
2. Why have governments and bureaucracies NOT required full spectrum acoustic measurement to be carried out at operating wind energy projects inside and outside homes, and why have the standards been written to preclude any requirement for such testing?
In other words, governments and the wind industry and its favourite acousticians have ensured that the very sound frequencies in the infrasound and low frequency noise ranges, established by Kelley and his co researchers to be directly causing the “annoyance” symptoms, are not being measured.