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Wind turbine infrasound: What’s all the noise about?

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On Wednesday the Senate inquiry into excessive noise from wind farms released their report. The inquiry was supposed to focus on audible noise but debate strayed into concerns that wind turbines can cause health problems by producing infrasound (sound of a frequency so low that it is normally inaudible) and low frequency noise.

Wind farm opposition groups such as the Waubra Foundation are prone to making extreme statements about wind turbines such as this from their senate inquiry submission “…characteristic symptom patterns have been reported at distances up 10km away from the nearest wind turbine.” Infrasound is blamed and understandably people get concerned.

So where does this idea come from? The Senate inquiry gives us the answers. Submissions represent a global who’s who in the debate on wind farms and health. Often information provided to support the wind-farms-cause-health-problems idea actually demonstrates the opposite.

Take for example Figure 1, presented by Steven Cooper of the Acoustic Group in senate inquiry submission no. 142. The Acoustics Group is used by opponents to wind farms in support of their submissions opposing proposed wind farms including: the Flyers Creek wind farm project in New South Wales and the Stony Gap and Hallet 3 projects in South Australia.

In presentations promoted by Senators Xenephon and Madigan, Cooper has quickly flashed through this graph and others in order to bolster the case that wind turbines could be causing health problems. I went to his presentation in Bacchus Marsh on 13th of June this year and witnessed this. Rather strangely, Cooper refused to provide a copy of his presentation even though he had just publicly presented it, despite requests from many members of the audience. What’s the secret? Particularly when Cooper goes to great lengths to say that “If there is potential for an industry to jeopardise the welfare, health or safety of the public, or affect the well being of the community I am duty bound to identify those issues under the Code of Ethics of the Australian Acoustical Society.” (inquiry submission no. 142).

Examination of Figure 1 shows that peak infrasound (sound below 20Hz that cannot usually be heard) recorded by Cooper inside a house near to a wind farm was about 50dB at very low sound frequencies of around 2Hz, fading quickly to almost nothing at 8Hz.

Now compare this to Figure 2, which shows the lowest threshold of ear sensitivity (the thick line on the lower edge of the grey shaded area) that Alec Salt believes is possible after tests conducted on cats and guinea pigs. Coopers recordings are well below Salt’s sensitivity threshold. This is significant given that Alec Salt’s work is also often relied on by wind farm opponents to support the idea that wind turbines are detrimental to health. Perhaps this is the reason for Cooper’s secrecy.

A second problem with the information presented by the Acoustics Group is also evident. Cooper did not isolate the cause of infrasound to wind turbines. He could simply be recording something else. To resolve this he needs to present data comparing infrasound with turbines on and off.

Figure (1) Infrasound measured inside a residence near to turbines by the Acoustics Group.

 

This shortcoming also resides in figure 2. Salt shows infrasound and low-frequency noise measurements from near wind turbines recorded by Van den Berg (2006) and Jung and Cheung (2008). By including this data in his graph Salt shows that very low frequency sound emissions from wind turbines could potentially be sensed by the ear even if inaudible. However neither Van den Berg or Jung and Cheung isolated the cause of infrasound by measuring with turbines turned off vs turbines turned on. They could have been measuring infrasound and low-frequency noise caused by the wind.

Infrasound and low-frequency noise measurements have however been conducted with wind turbines turned on versus turned off. Hepburn (2006) comprehensively measured infrasound around a wind farm in Alberta, Canada. Hepburn’s recordings 50m from wind turbines under high wind conditions (see below) show that the levels of infrasound and low-frequency sound recorded were very similar whether turbines were turned off or on as shown in figure (3).

In fact higher sound levels were recorded with turbines turned off versus when the turbines were running. A strong indication that the origin of most infrasound and low-frequency noise was the wind itself which was slowed by running turbines. Interestingly the results shown in figure 3 are consistent with the infrasound and low-frequency noise results shown by Salt in figure 2.

Infrasound from wind turbines is extremely unlikely to cause health problems, however wind turbines do on occasion cause annoyance due to audible noise. For example Van den Berg (2006) discusses a ‘beating’ phenomenon at one wind farm which could be amplitude modulation misinterpreted as an infrasound issue. Such phenomenon have resulted in changes to wind turbine noise standards in order that residents around wind farms are protected. For example the updated New Zealand Noise Standard 6808:2010 address amplitude modulation. Responsible changes are made to genuine problems. Those concerned about wind turbine noise should focus on audible noise and need not work themselves into a worry about infrasound.

Richard Mackie has a BE and ME in mechanical engineering majoring in control systems from the University of Auckland and an MBA from the Australian Graduate School of Management. He is the principal of Advanced Energy Consulting and consults to the wind energy industry.

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  • David Norman

    Richard, your notions on the possible sources of infrasound in the charts as depicted is certainly warranted given the absence of any indication of controls for background infrasound. However, in your closing sentence you jump to the unwarranted conclusion that the infrasound from Industrial Wind Turbines is not to “worry” about. You do not in fact have or present any scientific evidence to support this. Your approach is similar to that of Simon Chapman’s, sans the hyperbole. You both seek importance by denigrating others without proof and due process.

    • Neil

      David – what else would you conclude ? If the Hepburn study is correct, showing that the origin of most infrasound and low-frequency noise was the wind itself, then how can infrasound from a wind turbine be deletorious to health ? As noted elsewhere, we have been living in world surrounded by natural sources of infrasound with no obvious effects, why is it suddenly dangerous ?

      • George Papadopoulos

        Neil, let’s assume for a second that infrasound was a non-issue. Then why did the recent studies of Shepherd et al and Nissenbaum et al, find the people are getting ill around wind turbines?

        Sleep deprivation and stress, apparently consequences of audible noise, but perhaps something more than just that?

      • David Norman

        I did not infer that the Hepburn study was “incorrect” in terms of the manner and nature of the variables it measured. However I reject the assumptions you have made in relation to Industrial Wind Turbine infrasound and its effects on human health. If in fact there is an effect, as yet not proven or unproven, the co-variate relationship would need to be measured in the context of the “receptor”, that is within the building, eg; house, the translation of the infrasound vibration as a factor in potential health issues such as sleep disruption etc.. There is no quantitative physical or psycho-social research to demonstrate this contingency of Industrial Wind Turbine noise. There is however a great deal of undigested related research regarding “industrial noise and health” (google it) which indicates other forms of industrial noise are statistically significant dependent variables in a wide variety of human factors from cognitive development in children to cardiovascular implications. The implications of Industrial Wind Turbine noise and health will only be resolved by scientific research, not pseudo scientific narrative.

    • Ben Courtice

      David Norman: Guilty until proven innocent for turbines?

      In fact, there is plenty of evidence that turbines are harmless in this respect: inaudible levels of infrasound have never been demonstrated to have any medical effects; and no-one has been able to demonstrate that the inaudible infrasound from wind turbines is any different from any other inaudible infrasound in this respect. Or do you think that a complete lack of evidence is a convincing case to be suspicious? That wouldn’t be very logical.

      • George Papadopoulos

        Well according to Salt, quoted above, inaudible levels of infrasound DO cause physiological responses.

      • David Norman

        I “think that a complete lack of evidence is a convincing case to be” critical and demonstrate scientific due diligence.

    • http://etwasluft.blogspot.com.au/ Ketan Joshi

      David,

      Please demonstrate, with quotes from the article, how Mackie denigrates others.

      It seems, from my perspective, that the entirety of this article is simply examining the logic of the claims of various anti-wind groups, in the context of infrasound.

      I cannot see where the author resorts to denigration or mockery. Help us out.

      Thanks,
      Ketan

      • David Norman

        Ketan, you seem to be inordinately preoccupied with attempting to justify the confirmation bias of your perspective. I do not however see you as being disingenuous in this regard since this characteristic of ideology based narrative is inherent in its expression. As for your request for a “denigration” justifying quote, I use the Merriam Webster definition of “denigrate” which states; “to deny the importance or validy of”. And I quote from the article, “Responsible changes are made to genuine problems. Those concerned about wind turbine noise should focus on audible noise and need not work themselves into a worry about infrasound”. The first sentence infers that Industrial Wind Turbine infrasound vibration does not affect human health in the absence of direct quantitative co-variate scientific evidence. The following concluding sentence then goes on, in the absence of appropriate credential, to condescend a reassuring righteousness to this objectively unsubstantiated assertion. Does this not coincide with the definition of the word denigrate in your perspective?

        • http://etwasluft.blogspot.com.au Ketan Joshi

          Hi again David,

          - “The first sentence infers that Industrial Wind Turbine infrasound vibration does not affect human health in the absence of direct quantitative co-variate scientific evidence. ”

          That is untrue. “Infrasound from wind turbines is extremely unlikely to cause health problems” is the first sentence. Mackie refers to likelihood. He does not infer or state an absolute assertion.

          As a man of science, I am sure you understand that it is impossible to prove a negative. The burden of proof lies on the claimant, rather than the skeptic. I am quite sure you agree we ought not concern ourselves with unverified claims that have no basis in empirical reality. This is Mackie’s logic, and I feel it is, to some extent, your logic also.

          With reference to your quote, Mackie is simply offering advice, based on the conclusion he reaches from the examples he presents in the article.

          Some people are genuinely concerned about infrasound – Mackie is simply suggesting that concern is not warranted, based on our knowledge of low frequency noise emissions from various sources (including wind turbines).

          To state that Mackie’s closing sentence was denigrating is inaccurate. Suggesting people do not concern themselves, after having presented reasons for that assertion, is not classified as denigration.

          I feel you used the term mostly to shoehorn in a reference to Simon Chapman, as you have done on many other comment threads.

    • Richard

      David I am offended that you say that I seek to denigrate others. Quite the opposite. My article presents evidence to demonstrate that 1) infrasound noise measured inside a house is well below levels that Alec Salt says can theoretically be detected by the ear. 2) infrasound measured with turbines on versus off is very similar demonstrating that the infrasound from turbines is no different to infrasound from other sources like from the wind itself.

      The facts available to us are therefore something like:
      1. there is evidence that infrasound and low frequency noise from wind turbines is very low and extremely unlikely to cause health problems.
      2. the nocebo effect is real. It is proven that if people are told they will get sick then they can report symptoms of ill health.
      3. Sometimes audible noise issues related to wind turbines is a problem.

      Isn’t it therefore obvious that people living in the vicinity of wind turbines will be better off if:
      - they do not worry about infrasound as it’s not a problem.
      - scaremongering on false issues is avoided.
      - real audible noise issues are targeted and addressed.

      It seems logical to me that to do otherwise is to treat those living near to wind turbines an injustice.

      • George Papadopoulos

        Richard lots of assumptions, but little research on your behalf.

        Where is the evidence of “effective” scaremongering? You might find it interesting to read: Wagg, C., Butler, M., MacDermott, S.T., Johnson, M., & Scholfield, K. (2011) Hearing voices: A narrative analysis of the Senate Inquiry into the Social and Economic Impacts of Rural Wind Farms. Conference Proceedings: Sustainable Economic Growth for Regional Australia (SEGRA). Geelong, October 2011.

        In this paper you will realise that prior to the installation of wind turbines, people don’t take health issues serious. It is after installtion, when the concerns start.

      • David Norman

        Richard… you do indeed seek to denigrate. You are suggesting that the Pederson et al survey studies on which this premise of the nocebo effect of Industrial Wind Turbine noise is based, represents an objective quantitative measurements to verify this hypothesis. Whilst these studies do present a linear hypothesis indicator for further research in this area, they in no manner verify this assertion. The populist narrative of REneweconomy in this respect reflects a rhetoric that engages and expresses a dualism which designates those who report health effects as a result of Industrial Wind Turbine noise as expressing false notions which are simply the result of psychological impairment, for which you have no science based justification.

        • http://etwasluft.blogspot.com.au Ketan Joshi

          David,

          The nocebo effect, as hypothesised by Chapman, is not dysfunction or pathology, in the same way the placebo effect is not classified as pathology. (See Enck’s article in the NY Times here for a good overview – http://www.nytimes.com/2012/08/12/opinion/sunday/beware-the-nocebo-effect.html?_r=0 ).

          Please demonstrate, with references, where Richard Mackie claims that residents who report health effects are suffering from dysfunction or pathology.

          Cheers,
          Ketan

          • George Papadopoulos

            Ketan, have you forgotten the Portugese research that shows a peculiar pathology in people exposed to ILFN and vibrations?

  • Beat Odermatt

    OMG! If “infrasound” is dangerous, then living near the beach would be very dangerous. The movement of waves creates massive amounts of “infrasound”. It would be too dangerous to live anywhere where wind is interacting with water, rocks, trees, buildings etc. Maybe we could ask our Government to introduce a “Wind and Wave infrasound tax”. Anybody living near the beach, a building or is ever exposed to wind or the sound of waves would have to be taxed. I just hope that Nick Xenaphon and his mates are never exposed to forces of nature. It would be a taxing experience!

    • Mary

      Ignorant comment. Obviously you do not understand infrasound or low-frequency noise. The military uses it as a weapons system…..guess the wind industry does, too.

      • http://etwasluft.blogspot.com.au Ketan Joshi

        Mary,

        The military utilised infrasound at approximately 120 – 180 db, in their tests :
        http://schizophonia.com/archives/traumaArchive/Infrasound/DeadlySilence.html

        The infrasound emissions from wind farms, as Mackie states in the article, are at a sound level of ~50 – 75 db.

        As I am sure you know, sound is measured on a logarithmic scale, which means those numbers differ on an order of magnitude.

        That difference also happens to be the quantity by which you are wrong in your assertions.

        • George Papadopoulos

          Ketan your response actually vindicates what Mary is saying: to state that wind turbines produce 50-70dB is not at the wind turbines, but up to several km’s away (confirmed by Steve Cooper’s measurements).

          The noise level figure at the wind turbine is estimated to be about 120dB.

          If the military have developed LRADs then pay very careful to the acronym: “long-range accoustic devices”. 120dB is not 120dB at the target site.

          • http://etwasluft.blogspot.com.au Ketan Joshi

            George, you are indeed correct.

            The substantial number of Australia’s population living inside wind turbines now have good reason for concern.

            I will inform them of your findings, post haste.

            Sincerely,
            Ketan

  • http://aol.com Frank Haggerty

    In Massachusetts alone in the Town of Falmouth a residential community has over 50 residents sick from the low frequency sound .

    The Town of Fairhaven has ongoing complaints from a recent installation of two turbines.

    The Town of Scituate has even more complaints !

    How could hundreds of people all complain about the same noise issues over years .All these people can’t be lying !

    Besides the blade noise which you hear the loudest from the sides (aka random assault) there are gear box issues in most of the turbines installed after 2008.

    Portsmouth High School in Rhode Island, Princeton ,Massachusetts and Otis Air force Base have catastrophic gear box failures that require about a million dollars every three years to repair.

    The gear box failures could be part of the noise issues

    • Mary

      That’s so sad, Frank! The US Army is trying to find a way to direct low-frequency and impulsive sound because they know the levels required to debilitate 100% of the people 100% of the time. If this is a weapons system for the US military, it’s clear that the problem is real. They declassified some of their files on their research from 1996. I’m sure the experimentation is on-going.

  • George Michaelson

    I don’t think any discussion of Infrasound should be made without referring to the nocebo effect.

    The symptoms may be real. I’d be prepared to go firmer and say anyone who presents to a GP with symptoms in the anxiety/depression class, with high BP and sleeping problems or headaches has real symptoms. So, do they feel ill? are they ill? sure. Lets go there.

    But the assigning of *cause* to windfarms has to be taken in the context of nocebo: they may have latched onto windfarms as causative, and now cannot divorce from this.

    So, real symptoms, no causal connection, should this be a reason to not do wind farms?

    Sorry. I don’t think so.

    • Chris Fraser

      There could be an additional study on nocebo, maybe by the NH&MRC. The postulation is there is a direct and high correlation between numbers of people near a windfarm reporting increased illness – and the amount of local activism by the good folk of Waubra and like-minded groups.

      • George Papadopoulos

        Chris, has it even dawned on anyone, why there are “17 international reviews” on wind turbines and health, yet no government or wind industry group has ever bothered to directly research the issues?

        • Mary

          The wind industry is built on perceptions, not science, George. You won’t find them conducting actual, verifiable, quantifiable research on anything related to wind energy. Permitting is based on politics (mandates) and perceptions are used to influence people, including decision makers. There is NO science to support industrial wind. In fact, FAA documents obtained via FOIA from Cape Wind revealed that industrial wind turbines create micro-climate change. It’s political nonsense, a power play that will have devastating environmental consequences. Real science from USFWS cites a 47% loss of raptors where industrial wind is installed. IA DNR agent cites a 42% loss of other birds. Habitat fragmentation by industrial wind is horrifying because they fragment both the land and the air corridor. The money changing hands is also based on perceptions. Green tags, those things bought and sold on the green energy exchange, are based on perceived value. This is nothing more than another bubble being created and people who lack the ability to discern fact from fiction or perceptions from reality are supporting it.

          • Beat Odermatt

            I, like tens of thousands of other people around the world, had worked in the coal mining industry. When I had a shower, the water turned black and when I did blow my nose, the tissues did become black. Most of us worked in these areas to provide a good future for our children. I may have been lucky enough to have (touch wood) not having health problems due to coal dust and continuous exposure to emission from spontaneous combustion.
            The coal mining industry has provided a lot to the economy of Australia as did the horse during the times of our pioneers. Times have changed and we can move on to a cleaner and healthier future and wind clean, safe wind energy is one of the means. Old fashioned narrow minded future haters like you work in desperation to stop a cleaner brighter future. Sadly enough you have help from narrow minded selfish show pony politicians like Nick Xenaphon.
            I just wish that you and your narrow minded bunch of future haters could be in a coal mine for a year or so. It may help you to come to your senses.

          • http://etwasluft.blogspot.com.au Ketan Joshi

            Hi Mary,

            Wind farms do not create ‘micro climate change’. This is a myth spawned by Fox News, and sustained by climate skeptics See:
            http://www.washingtonpost.com/blogs/wonkblog/post/no-wind-farms-are-not-causing-global-warming/2012/04/30/gIQAMl2GsT_blog.html

            Here’s the FWS study you cite. There’s no mention of raptors, and the number 47%’ doesn’t show up on a search:

            http://www.fws.gov/habitatconservation/wind.pdf

            As for the IA DNR, I literally cannot find the study you refer to. It might be worthwhile citing and hyperlinking your sources, when you make claims. Unless, of course, the very sources you cite disprove the point you are trying to push, in which case, I suggest you continue as-is.

            I think you said it best yourself:

            “This is nothing more than another bubble being created and people who lack the ability to discern fact from fiction or perceptions from reality are supporting it.”

        • Richard

          George your comment is rubbish. Low frequency noise including infrasound has been studied directly by many government departments, pretty well as soon as it was thought that there may be a problem. One of these reports is “The measurement of low frequency noise at three UK wind farms” in 2006 by Hayes Mckenzie Partnership Ltd for the Department of Trade and Industry in the UK. You can look it up on the internet.

      • Chris Fraser

        Because no rational government has made a direct causal link from low frequency turbine sound to illness.

    • Blair Donaldson

      Frank, got any links to credible research to back up your assertions?

  • Chris Fraser

    So the Alberta study appears to show the source of low frequency noise is the wind itself with a difference of only 10db ? Considering 30 dbA is a dead quiet library at 2m that must be undifferentiable. You’d think that would add up for even the most ingrained and bigoted anti-wind activist.

    • George Papadopoulos

      “Dead quiet library”. I’m sorry to say, but my rural property is less than 20dBA when it is “dead quiet”. Did someone forget to turn the air conditioner off?

  • http://telstrabroardband Bruce

    Good on you Mary, if you can’t sleep in every 24 hours you have a problem in your health and the noise from wind turbines create the problem in your health. This is not rocket science either.

    • Beat Odermatt

      There could be evidence that people neat windmill and near the beach actually sleep better then people in cities. Worry about doomsday and stay awake all night!