Wind Turbine Infrasound: What Drives Wind Farm Neighbours to Despair

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To call the mood amongst the wind industry, its parasites and spruikers “hysterical” is mastery in understatement. Their future is not just dark and dismal; it’s heading from catastrophic to cataclysmic.

On every battlefront the wind industry is taking a pounding.

As you would expect from any beleaguered force, the reaction to the inevitable collapse of the wind industry isn’t pretty.

Having lost the grip on the game in countries where they thought they had things sewn up, they’ve been reduced to abusing those who have the ability to make or break them. STT thinks they’re just working through the 5 stages of grief: denial, anger, bargaining, depression and acceptance (see our post here).

Among the growing list of what’s getting to them, is the fact that – despite efforts to cover up both the work and the results – highly skilled people are working flat out around the world to discover the precise mechanism that causes the adverse health effects from incessant turbine generated low-frequency noise and infrasound, including sleep deprivation.

It’s not only the fact of their rather obvious conclusions that has the wind-spinners in apoplexy, it’s the fact that they’re looking at all.

You see, the line being run is that there is NO problem – a tobacco advertising guru said so – so why on earth should anyone be looking?

For the wind industry and its parasites, the problem is, that there IS a problem: teams of highly skilled scientific investigators don’t generally devote their every waking hour to chase answers and solutions, when there’s nothing to chase.

Here’s just another example of what properly qualified people can do when looking for answers to real problems.

Infrasound/low-frequency noise and wind turbines
Report for Multi-Municipal Wind Turbine Working Group
Keith Stelling
July 2015

Executive summary
Typically, regulating authorities have not required the measurement of infrasound (sound below 20 Hz in frequency) and low frequency (LFN) (generally sound from 200 Hz to 20 Hz) inside homes adjacent to wind turbines as a condition of their installation and operational monitoring. The health risk of infrasound from wind turbines has been dismissed by the wind industry as insignificant. It has maintained that since the typical loudness and frequency of wind turbine sound within a home is not audible, it cannot have any effect on human health.

Noise measurements for most studies and environmental assessments have been limited to the measurement of audible sound outside homes– using dBA weighted monitoring which is insensitive to infrasound frequencies. Some studies and environmental assessments have even relied on projected audible sound averages from computer produced models.

Such observations and projections fail to take appropriate account of the distinguishing signature of the sound from a wind turbine. Unlike the more random naturally occurring sounds (such as wind or lake waves which may themselves have an infrasound component), the sound from wind turbines displays characteristics that produce a pattern that the ear and audio processing in the brain recognize. Our hearing is strongly influenced by pattern recognition. (This is why we can pick out the sound of a familiar voice even in a crowded room with many people speaking).

One recognizable wind turbine pattern is a tonal signal of sharply rising and falling pulses in the infrasound range, (typically about 0.75 Hz, 1.5 Hz, 2.25 Hz, 3.0 Hz, and so on). It is produced by the blade passing the tower. At this frequency these pulses may be “felt or sensed” more than “heard” by the ears. Research by Dr. Alec Salt and others has demonstrated that subaudible infrasound does result in a physiological response from various systems within the body.

The second recognizable pattern is the amplitude modulation. This is the typical “swoosh” rising and falling that is audible.

A third recognizable pattern of sound from wind turbines results from the equipment in the nacelle (such as the gearbox if the turbine has one) and ventilating fans. Although in some cases this third sound source may become predominant, it is usually of lesser effect that the first two.

We now know that subaudible pulsating infrasound can be detected inside homes near operating wind turbines. It can also be identified up to 10 kilometres distant. We know also that very low levels of infrasound and LFN are registered by the nervous system and affect the body even though they cannot be heard. The research cited in this report implicates these infrasonic pulsations as the cause of some of the most commonly reported “sensations” experienced by many people living close to wind turbines including chronic sleep disturbance, dizziness, tinnitus, heart palpitations, vibrations and pressure sensations in the head and chest etc.

Similarly, there is medical research (also cited below) which demonstrates that pulsating infrasound can be a direct cause of sleep disturbance. In clinical medicine, chronic sleep interruption and deprivation is acknowledged as a trigger of serious health problems.

I. The work of Neil Kelley

1979: First report of human distress from wind turbines

The first wind turbine noise complaints in North America, reported over 35 years ago, sound strikingly familiar today. Residents living within 3 kilometres of a 2 MW wind turbine near Boone, North Carolina, described a periodic “thumping” sound accompanied by vibrations. Many said that they could “feel” more than hear the sounds. They spoke of repetitive sleep disturbance and maintained that the sounds were louder and more annoying inside their homes than outside; some became more sensitive to the impact over time.

The overlooked documents on wind turbine infrasound

In response to the complaints from Boone, the U.S. Department of Energy and the National Aeronautics and Space Administration (NASA) commissioned Dr. Neil Kelley and his colleagues at the Solar Research Institute (which later became the National Renewable Energy Laboratories of the US Department of Energy) to investigate possible causes. Over the next ten years, Kelley was able to take advantage of government and NASA facilities and funding to carry out extensive field investigations and laboratory research of a scope and thoroughness that has not been matched since. He also had access to experts at six leading American Universities as well as the co-operation and input of the wind turbine industry.

Between 1982 and 1988, Kelley and his colleagues published five important papers:

1. N. D. Kelley, R. R. Hemphill, M. E. McKenna. “A Methodology for Assessment of Wind Turbine Noise Generation”, 1982. (First published in J. Solar Engineering, Vol. 21 (1981), pp.341-356).
2. E. W. Jacobs, N. D. Kelley, H. E. McKenna, N. J. Birkenheuer. “Wake Characteristics of the MOD-2 Wind Turbine at Medicine Bow, Wyoming”. November 1984.
3. N. D. Kelley, H. E. McKenna, R. R. Hemphill, C. l. Etter, R. l. Garrelts, N. C. Linn. “Acoustic Noise Associated with the MOD-1 Wind Turbine: Its Source, Impact, and Control”. February 1985. (First published by the Solar Energy Research Institute, February 1985). (262 pages)
4. N.D. Kelley. “A Proposed Metric for Assessing the Potential of Community Annoyance from Wind Turbine Low-Frequency Noise Emissions”, November 1987.
5. N. D. Kelley, H. E. McKenna, E. W. Jacobs, R. R. Hemphill, J. Birkenheuer. “The MOD-2 Wind Turbine: Aeroacoustical Noise Sources, Emissions, and Potential Impact”. Solar Energy Research Institute. Prepared for the U.S. Department of Energy, January 1988.

His work was published in peer reviewed journals. He presented his paper “Acoustic Noise Associated with the MOD-1 Wind Turbine: Its Source, Impact, and Control” at the Fourth ASME (American Society of Mechanical Engineers) Wind Energy Symposium held in Dallas, Texas on 18-20 February 1985. In 1987 he presented his paper “A Proposed Metric for Assessing the Potential of Community Annoyance from Wind Turbine Low-Frequency Noise Emissions”, at the American Wind Energy Association “Windpower ’87 Conference and Exposition”, October 5-8, 1987 in San Francisco, California.

The NASA investigation by Dr. Neil Kelley and his colleagues established a link between wind turbine generated impulsive infrasound and low frequency noise and the symptoms (including sleep disturbance) reported by the Boone, North Carolina residents.

The first report was based on three years of detailed field research. It recorded the experiences of actual people living near turbines through their resident diaries. It involved a complete set of full spectrum acoustic measurements (not estimated computer projections limited to A-weighted sound) extended over the entire 3 year study period. It included sound and vibration measurements as well as detailed meteorological observations.

It was followed by the publication of the results of subsequent laboratory research. Human volunteers were directly exposed in the laboratory to some of the sound energy in the infrasound and low frequency noise frequencies similar to the wind turbine measurements. The individual human responses confirmed an association between infrasound/LFN and the distress experienced by the volunteers.

Kelley’s key findings 

(1) Wind turbines emit infrasound

• “The modern wind turbine radiates its peak sound power (energy) in the very low frequency (VLF) range, typically between 1 and 10 Hz.”

(2) Wind turbine infrasound and low frequency noise is often subaudible.

• “The detailed analysis of a series of acoustic measurements taken near several large wind turbines (100 kW and above) has identified the maximum acoustic energy as being concentrated in the low-frequency audible and subaudible ranges, usually less than 100 Hz”.

(3) Wind turbine infrasound and LFN is characteristically impulsive (pulsating, containing spikes or peaks and valleys).

• “Impulsive noise, such as has been found with the MOD-1, is identified with short, transient fluctuations in the radiated acoustic field which can contain considerable energy”.

(4) Community annoyance described by residents

• “Residents living in affected houses reported periodic “thumping” sounds accompanied by vibrations”.
• Many said that they could “feel” more than hear the sounds.
• They spoke of repetitive sleep disturbance.
• “These field measurements and model results allowed us to conclude the following: The annoyance was real and not imagined”.

(5) Community annoyance is related to impulsiveness

• “These measurements have also shown any reported community annoyance associated with turbine operations has often been related to the degree of coherent impulsiveness present and the subsequent harmonic coupling of acoustic energy to residential structures”.

(6) Wind turbine disturbance is detected more inside houses than outside.

• “Residents reported the sounds were louder and more annoying inside their homes than outside”.
• “Experience with wind turbines has shown that it is possible, under the right circumstances, for low-frequency (LF) acoustic noise radiated from the turbine rotor to interact with residential structures of nearby communities and annoy the occupants”.
• “An extensive investigation . . . revealed that this annoyance was the result of a coupling of the turbine’s impulsive LF acoustic energy into the structures of some of the surrounding homes. This often created an annoyance environment that was frequently confined to within the home itself”.
• “The strong resonant behavior of the indoor pressure field when excited by an external impulsive excitation, all point to a complex resonance condition between the volume of air in the rooms and the vibration (displacement) of the walls and floors surrounding it”.
• “We found that the periodic loading by the MOD-1 [wind turbine]impulses excited a range of structural resonances within the homes measured”.

(7) Sound measurements and residents’ reactions (diarized) were compared

• “These results, limited as they are, seem to confirm that people do indeed react to a low frequency noise environment and A-weighted measurements are not an adequate indicator of annoyance when low frequencies are dominant”.

(8) A structural pattern differentiates turbine emissions from background noise

• “The acoustic pressure patterns radiated from large wind turbines have a definite structure as compared with the natural, wind-induced background”.15 [IWT emissions are different from background noise.]
• “The acoustic pressure patterns radiated from large wind turbines have a definite structure as compared with the natural, wind-induced background”.

(9) Human body resonances associated with annoyance

• “We hypothesize one of the causal factors related to the annoyance associated with the pulsating pressure fields in the rooms measured is a coupling with human body resonances which in turn are responsible for creating the sensation of a whole-body vibration. This perception is more noticeable indoors due to the increased reverberation time and dynamic overpressures from the interaction between the structural and air volume resonances.
• “There is evidence that the strong resonances found in the acoustic pressure field within rooms actually measured indicates a coupling of subaudible energy to human body resonances at 5, 12, and 17-25 Hz, resulting in a sensation of whole-body vibration”.

(11) A-weighted measurements inadequately indicate low frequency annoyance

• “A-weighted measurements are not an adequate indicator of annoyance when low frequencies are dominant”.

Industry denies wind turbine infrasound emissions

For nearly three decades Kelley’s work has been overlooked or intentionally sidestepped. The industry has continued to deny that wind turbines emit infrasound or that it affects nearby residents. In 2009 Robert Hornung of CanWEA misadvised the Ontario Ministry of the Environment:

“No peer-reviewed study has ever established a link between infrasound from turbines and human health. . .”.

In responding to the recent re-discovery of Kelley’s research by the public, Australian Clean Energy Council policy director Russell Marsh said the study was not relevant to modern turbines. “This is the equivalent of taking a study about Ataris and applying it to the latest iPads,” Mr. Marsh said.

However, the latest much larger wind turbines have been found to emit even more infrasound.

Keith Stelling, MA,(McMaster) MNIMH, MCPP (England)

Access the full report here: Infrasound-wind-turbines-Stelling July-2015

For a detailed wrap-up of the wind industry’s efforts to cover up the decade’s worth of highly relevant work done by Neil Kelley and others for NASA, see our timeline here:

Three Decades of Wind Industry Deception: A Chronology of a Global Conspiracy of Silence and Subterfuge

Keith Stelling also refers to the ‘Atari Defence’ cooked up by STT favourite, ‘Rusty’ Marsh from the Clean Energy Council. STT covered that piece of piffle some time back:

Some facts that wind weasels would have rather kept buried

The NHMRC: Australia’s Great Shame

For a taste of what Rusty’s ‘latest iPads’ sound like, cop an earful of this: