Wind Turbine Noise and understanding the Spectrum of Noise, Infrasound and Low Frequency Noise (ILFN) and why ETSU-R-97 is unfit for purpose

Posted Category: Health, Low Frequency Noise, Wind turbine Noise

This update includes: Irish Court Judgement on 12th December 2019

and Summary of Finish Study 

1. ETSU- R-97

 I would like to explain why current ETSU-R-97 noise guidance (not legislation) will not protect windfarm neighbours from noise including Infrasound and Low Frequency Noise -ILFN. The public are not adequately protected by this out-dated guidance.

Names we know, Marcus Trinick QC, Malcolm Hayes (Hayes McKenzie Partnership), Mark Jiggins (formerly of then Carrick District Council now of Hoare Lea Acoustics) and Dr Andrew Bullmore of Hoare Lea and Partners, were members of the original noise working group commissioned by the Department of Trade and Industry (DTI), which became the Department of Energy and Climate Change (DECC) and is now the Department of Business Energy and Industrial Strategy (DBEIS)) to formulate noise guidance for wind turbines. Full document available here

 “This report describes the findings of a Working Group on Wind Turbine Noise. The aim of the Working Group was to provide information and advice to developers and planners on the environmental assessment of noise from wind turbines. While the DTI facilitated the establishment of this Noise Working Group this report is not a report of Government and should not be thought of in any way as replacing the advice contained within relevant Government guidance. (Effectively there is none!)

The report represents the consensus view of the group of experts listed below who between them have a breadth and depth of experience in assessing and controlling the environmental impact of noise from wind farms. This consensus view has been arrived at through negotiation and compromise and in recognition of the value of achieving a common approach to the assessment of noise from wind turbines.” Full document available here

This ‘Bad Science’ behind the wind turbine noise guidance, adopted here in Scotland and by most countries around the world, is discussed by the Independent Noise Working Group INWG:

“The critical factor is that ETSU prevents local authorities from exercising duty of care responsibilities.”

The Planners and Environmental Health Officers (EHOs) are informed by, and dependent on this ETSU guidance as well as being advised by acoustic consultants employed directly by the wind farm operator for investigation of cases of Wind Turbine Noise (WTN) complaints.

This concern was raised in 2003 by Hazel Guest, UK Noise Association 5th March 2003 ABSTRACT “Knowledge of the latest results in Low Frequency Noise (LFN) and infrasound research are not being transmitted, either to government whose job it is to legislate on standards of noise and vibration, or to local authority officers whose job it is to look into complaints and enforce standards. The dismissal of complaints is frequently based on inappropriate techniques such as the application of A-weighting, a lack of understanding of vibration transmission including building resonance, and a lack of basic understanding about the perception of low frequencies by complainants, for instance the lowering of the lower audibility threshold arising from exposure. This paper asks those involved in research to ensure that their relevant findings are more widely disseminated, along with advice to legislators and local authorities on measurement, information on LF and infrasound resonance in buildings, recommendations for appropriate standards to be used in assessing LF and infrasound as a Statutory Nuisance, and information about the effects of long term exposure. There is a need for more research in situ into specific effects.” Full document available here

It is of note that ETSU-R-97 guidance only covers wind turbine audible noise. Did the members of the ETSU working group have something to hide when they devised guidance that only covered audible noise?

It is also of note that all other environmental noise is the responsibility of The Department for Environment, Food and Rural Affairs (DEFRA), the government department responsible for environmental protection.

Questions about ILFN have been raised with ministers and departments on many occasions, usually responded to by civil servants in a very unsatisfactory manner.  A number of MPs have raised questions in the House of Commons and Scottish MP Bill Grant raised the matter on my behalf in the House of Commons on Tuesday 12th September 2017 [1]. Then Energy Minister Richard Harrington, on behalf of the Secretary of State for DBEIS, answered “that the potential impact on human health of these turbines is a topical issue, so it will attract further study, both in the UK and abroad, and we are monitoring that carefully.”

Bill Grant MP raised the matter again recently [2] and asked the Energy Minister Kwasi Kwarteng,  “what assessment her department has made of the potential effects of (a) low-frequency sound and (b) amplitude modulation from onshore wind turbines on (i) public health and (ii) quality of life. (4347)”. His answer on behalf of the Secretary of State for DBEIS, Andrea Leadsom: “In 2016 the department for Energy and Climate Change published a report which makes recommendations for how local planning authorities can assess amplitude modulation and use planning to control it where necessary.”

This response avoided the first question and demonstrates that DBEIS is doing nothing to address the real concerns or take on board the recommendations of the World Health Organisation Environmental Noise Guidelines 2018 with regard to wind turbine noise.



2. World Health Organisation Environmental Noise Guidelines 2018

 Although the World Health Organisation (WHO) has previously published “Environmental Noise Guidelines” (in 1999 and 2009) the 2018 edition is the first to consider wind turbine noise. “There are serious issues with noise exposure assessment related to wind turbines.” “Standard methods of measuring sound, most commonly including A-weighting, may not capture the low-frequency sound and amplitude modulation characteristic of wind turbine noise… » Based on all these factors, it may be concluded that the acoustical description of wind turbine noise by means of Lden or Lnight may be a poor characterization of wind turbine noise and may limit the ability to observe associations between wind turbine noise and health outcomes.”

This is also supported by Dr John Yelland MA DPhil (Oxon) MInstP FIET AMASA MIOA who describes the importance of the WHO Noise Guidelines with reference to Wind Turbine Noise and stresses the importance of the “Precautionary Principle” Dr. J Yelland Note on importance of WHO 2018 Noise Guidelines ref Wind Turbine Noise.

3. Infrasound and Low Frequency Noise

Working closely with Mariana Alves- Pereira, Bruce Rapley, Huub Bakker, Rachel Summers, along with Dr John Yelland and Melvin Grosvenor, we are able to provide data which demonstrates that turbines will be an agent of disease to affected windfarm neighbours.

I have quoted Professor Mariana Alves-Pereria of the Lusofona University in Portugal who has degrees in physics and biomedical engineering, and a PhD in environmental science. This  recent presentation by Professor Mariana Alves-Pereria, with full explanations and cause and effect can be found here.

Infrasound and Low Frequency Noise (ILFN) are a physical Agent of Disease:

In the terms of physics, ‘sound’ is an airborne pressure wave which hits the body. These pressure waves can vary in time, amplitude and frequency. WHO calls this noise from man-made sources: Inanimate Mechanical Forces

These pressure wave forces on the body are no different to you being in a boxing ring and being hit by a boxer. In the terms of Physics, it is an airborne pressure wave which hits the body whether we hear it or not.  A low energy pressure wave over a long time can be shown to have damaging effects on the human body.

Hertz (Hz) is the frequency or pitch of the sound and is measured by the distance between the peaks known as the wavelength. For audible noise the peaks are close together which is why we can hear it and the wavelength is in the order of centimetres. Humans hear well at 3000Hz (babies cry at 3500Hz). To protect against noise, a barrier has to be the thickness of the wavelength which is achievable for audible noise. But at 20 Hz the wavelength is 17 metres, so we do not have the means of creating a barrier, of sufficient thickness, to protect from these lower frequencies. Because of the high energy within low frequency pressure waves, low frequency sound will travel through barriers and may cause them to resonate in response to the sound stimulation within enclosed spaces. The Finnish Association for Environmental Health, SYTe, started measuring infrasound from wind turbines at seven different locations in Finland in the first half of April 2019. According to the results from May–June the infrasound, from wind turbines can be measured at a distance of at least 30-60 km from the wind farms.

Historically, acousticians have only considered audible noise as scientists only concentrated on what we could hear and preventing deafness and damage to ear canals. What we hear is a combination of frequency and amplitude. As the frequency goes down, we need higher and higher energy to perceive the sound. The dBA scale is designed to emulate the levels of equal loudness at frequencies within the human audible range and which can be used to protect hearing. Most legislation around the world is established around the audible decibel (dBA). 800Hz – 7000Hz is where we hear very well, which is the area of measurement that the dBA is designed to protect (A -audible- Weighted). There is no difference between the dBA measurement and what is, de facto, present in the environment. While the dBA weighting does not take into account noise below 20Hz on the basis that it is not audible. Noise below 20Hz is still able to be perceived by humans and forms part of the detection of danger for the fight or flight response (Rapley, 2018)

Institute of Acoustic (IOA) acousticians who are commissioned to assess wind turbine noise impacts for wind turbine developer’s environmental statements, state that humans are generally not aware of the presence of infrasound.  However, there is a difference between how a human, animal or bird responds to the character and signature of the sound from an earthquake as opposed to the sound from the sea.  For example, the sea may be deemed soothing and an earthquake frightening.  Both sounds produce different responses in a person (animal or bird) without them necessarily perceiving them audibly.

At the same time, it has been said that ‘what you cannot hear cannot harm you’. On a parallel note we could also say ‘what we cannot see cannot harm us’, but we know humans cannot see UV radiation but do get sunburnt, nor can they see x-rays but may develop cancer due to over exposure.  Therefore, we must be cautious of discounting phenomena we cannot perceive either visually or audibly.

The dBA is totally inappropriate when you measure ILFN as at 10 Hz there is a deduction in measurement of 70 dB. In an analogy, imagine a speedometer on a car displaying it is travelling at 70mph when in fact the vehicle is stationary, or the other way around and you are travelling at 70mph and the speedometer displays that you are travelling at 0mph. It is an error of 70mph which is the same as measuring infrasound at 10Hz when there is actually an error of 70dB.

The option of measurement to quantify what ‘sound’ is actually emitted is the dB linear range.

The above visualisation is courtesy of Steven Cooper and as can be seen it is constantly varying in frequency and amplitude. The dBA does not correctly represent the ‘noise’ to which we are exposed – it never goes above 40 dBA (the left-hand bar). Only when measuring in dB linear can we see what we are actually exposed to (the right-hand bar).

                                                                         One Third Octave Band Analysis Graphs

The red bars in the graphs above, are measurements in dBAs as required by regulation. As can be seen dBA levels (red bars) do not change very much whether the wind turbines are turning or not. The grey bars are measured in dB linear and show the vast difference to what you are exposed to when the turbines are turning compared to when they are not. This graph is called a One Third Octave Band Analysis and is an average of a ten-minute measurement.

Now we can measure to include the time. These graphs below show the same data as in the graph above, but these include time:

                                                            One Third Octave Band Analysis Graphs in real Time

The brighter colours show the higher acoustic energy produced when the turbines are rotating. You will also notice that the bright colours are not a continuous line. If it was a continuous line it would be a continuous ‘hum’, the broken line shows a pulse. That’s what we see when analysed scientifically and not as regulation requires. We do not get this data in noise impact assessments if measured according ETSU-R-97 noise guidance.


This is the exact same data again as the previous graphs. The two graphs in the bottom right relate to the blue line and the two graphs in the top left to the red line. The blue line is when the turbines are not rotating, and the red line is when the turbines are rotating. This is called the Harmonic Series. This is a mathematical tool which scientists use to study periodic events – peaks. As you can see from this Harmonics graph these peaks fall exactly on a mathematical series, – it is not ‘wind’ (or the ocean) –natural infrasound does not fall on a mathematical series, rather it is similar to white noise. The harmonic series is what is called the wind turbine acoustic signature and it is the agent of disease windfarm neighbours are subjected to under current UK and often world-wide regulation.

As stated in the current WHO noise guidelines – Annex 1, “Standard methods of measuring sound, most commonly including A-weighting, do not capture the low-frequency sound and amplitude modulation characteristic of wind turbine noise… »

The following two graphs demonstrate the vast difference as to what acoustic energy is shown when measuring audible noise only (A Weighting used by wind industry acousticians) compared to measuring the full spectrum of noise (Unweighted). A Weighting is designed to filter out low frequency noise and should not be used if there is a possibility of a predominance of ILFN. We can see below that using A Weighting there would appear to be nothing in the noise environment to be concerned about, whereas Unweighted shows the high level of ILFN.

                                                                                A Weighted Noise Spectrum

                                                                                      Unweighted Noise Spectrum

In these examples two microphones have simultaneously recorded the environmental sound pressure waves; the red one inside and the blue outside. Below is the real time data and harmonics from the above recordings. The brighter colours show the higher (mostly inaudible) acoustic energy produced when the turbines are rotating. You will also notice that the bright colours are not a continuous line demonstrating the existence of a pulse.

                                                                                                                       Blue Time Plots

                                                                                                                             Red Time Plots

                                                                                                             Blue Harmonics 

                                                                                                            Red Harmonics

The harmonic series is identified as the wind turbine acoustic signature and it is the agent of disease windfarm neighbours are subjected to under current UK guidance. Noise from industrial sources produce peaks which fall exactly on a mathematical series which indicates that it is An Inanimate Mechanical Force.

 Further reports on noise monitoring in Scotland can be found in Appendix

Increasing numbers of wind turbine noise complaints are of serious concern. Councils in Scotland and around the world are failing to adequately respond to these complaints in order to protect, and in some cases, seriously affected local residents. Current complaint procedures and policy, requiring the perpetrator such as the wind turbine operators to monitor and assess levels of WTN pollution, is failing victims. They are fobbed off with Acoustician’s Wind Turbine Noise Reports which are not fit for purpose by unprincipled acousticians who often rely on Professor Geoff Leventhall’s hypothesis that ‘wind turbine noise syndrome is all in the mind’.  He recently demonstrated this in his paper, presented at the 8th International Conference on Wind Turbine Noise Lisbon – 12th to 14th June 2019. Download document here:

 I can still hear it and it’s making me ill”

 “The paper has considered those who respond acutely to nearby wind turbines, giving consideration to those who exhibit the most severe responses and have, through no fault of their own, been unable to adapt to the changes in their environment which accompany the introduction of wind turbines. Explanations for the severity of their responses are attempted, but this is a very difficult area. It is possible that severity of responses has been influenced by the strong anti-windfarm campaigns which raise fears of effects on health, but adverse effects can be rolled back by therapies such as CBT” (Cognitive Behaviour Therapy).

Noise complaints are rarely upheld, Environmental Health Officers who lack expertise are advised by the wind energy operators acousticians. Many who complain about noise issues have equipment installed for over twelve months without any conclusive results. These people are living in unsellable homes in torturous conditions, with ruined amenity and health. Homes have been abandoned and some are occasionally bought out by the operator complete with gagging order which covers up the true extent of all suffering residents.

4. Further Analysis looks at other recent judgements / research around the world.

  • There was very significant decision from the Supreme Court in Ireland on 12th December 2019.

A wind farm in Cork was defeated on the grounds that the Irish Wind Energy Guidelines which date from 2006 are no longer adequate in measuring the true nature of wind turbine noise, that our knowledge of the specific characteristics of wind turbine noise has evolved over the years and that measuring the dBA only is not a true measure of all the noise from a wind farm.

Read the Court Judgement here

Down load the summary here The increase in height, number and efficiency of wind turbines will prove to be very damaging to the communities in the area similar to those described in the summary.

  • Analysis of the WHO Environmental Noise Guidelines for the European Region 2018 and wind power noise effects on man and the environment By Ove Björklund 2019-03-26 The association God Livsmiljö Hylte, Sweden (God Living Environment)

Member of EPAW – European Platform Against Windpower

This Analysis looks at other studies around the world.  See Appendix 2

This paper also looks at ground vibration and the impacts on the ground, climate, forestry and peat, including studies on Ecosystems and Biodiversity and insect damage.

“Scientific research and citizens’ “truth documents” show that Europe is already exposed to extreme depressive burden with land-based wind power. Evaluation of the serious health, climate and environmental problems has long been blocked by the Union’s authorities and political systems. The injuries are already partially irreparable and complaints and public health effects cynically abducted. Citizens who are exposed to major health risks and private-financial losses are denied the right to speak up to the Supreme Court, while international companies are given the right to make incorrect decision-making documents without the intervention of the authorities. Legal certainty is questioned by large groups of citizens. It is no longer about marginal electoral groups in sparsely populated areas, but now also touches people in the larger central cities. The parties behind the energy policy maintain the conditions and policies, and the population’s sense of exclusion is increasing.”

It examines how the wind industry are in breach of the Aarhus Convention and looks at how EPAW is playing a growing role in bringing about an end to this appalling situation.

It also examines the European Political response to this

5. Conclusion:

 This paper is calling for a complete independent over hall of the guidance and regulation of wind turbine noise impact and compliance assessments.

Due to the continuous deployment of increasing size and numbers of industrial wind turbines, in less suitable locations ever closer to homes, cumulative noise impacts are not being adequately addressed. The effect of low frequency noise radiating from different locations, depending on topography, has the potential to resonate where the pressure waves meet. This cumulative effect will cause vulnerable wind turbine victims to be impacted from more than one direction at a time. This will seriously impact many homes and lives within local environments.

 “That noise complaints from within communities and by local residents need to be taken seriously as being well founded and legitimate. They should be thoroughly investigated and that there should be no attempts to undermine these complaints as being as a result of mere ‘annoyance’ due to a perceived notion that complainants just don’t like wind turbines or are even motivated by other non-acoustical factors.”  Review of WSP/Parsons Brinckerhoff and Institute of Acoustics Amplitude Modulation Studies 

 Susan Crosthwaite

30th November 2019

Updated 17.01.2020

5 Responses to "Wind Turbine Noise and understanding the Spectrum of Noise, Infrasound and Low Frequency Noise (ILFN) and why ETSU-R-97 is unfit for purpose"
  1. RICK DRAKE says:

    Outstanding work here. But please, I say again, This problem is not only wind turbines it also applies to any machine that produces this LFN and infrasound.

  2. Admin says:

    Thank you. Yes we are well aware of this and are looking into other sources causing problems for people.

  3. LES HOWARTH says:

    Excellent report! … I have an INFRASOUND problem to share caused by a local wind farm. We live in a village called Hurst Green (Lancashire) in an Area of Outstanding Natural Beauty which is 13 miles north of the Hyndburn Wind Farm. The village elevation is 400 feet above see level and we have line of sight of this wind farm which was completed in 2012 and currently has 12 turbines. I didn’t realise until recently that the disturbing noise a number of people in the village have reported hearing (inside houses) is attributed to INFRASOUND. Since the Covid-19 lockdown in March 2020 the annoying sound has become constant (day and night) which is probably due to the reduction in traffic and the closure of many local businesses and factories.

    I fear many local authorities like ours don’t have the skills or resources to understand this problem or are paralysed to investigate due to the financial incentives and legislation to build wind farms -more communities will experience the same problem. For people who can’t relocate they must learn to live with INFRASOUND or find a solution to block/interfere with the deep low frequency HUM. From my investigations so far there doen’t appear to be any solutions to stop INFRASOUND indoors and cognitive behaviour therapy does not stop the noise.

    I would like to point out I am not against wind farm technology and understand we have to provide green energy. However, if any wind farm has sub-standard equipment/gears that generate unnecessary noise which generates long range INFRASOUND to the detriment of quality of life there should be laws to protect us. This might also include compensation, fines, machinery replacement and perhaps research into building materials that reduce resonance problem in areas that fall within the “infrasound range” of any wind farm.

    Your article has links to excellent scientific evidence proving INFRASOUND and noise pollution from wind farms is an increasing problem. I hope more effort to raise awareness and gather support to introduce new laws is a sensible way to reduce INFRASOUND as wind farm numbers are likely to increase. Possibly preventing wind farms operating during the night or new regulations to install BETTER turbines and machinery will help. I understand wind farm technology is taken seriously in Scandinavia who invest in noise reducing equipment.

    To anyone reading this who has not experienced INFRASOUND it is very much like the sound of your fridge motor running which you may hear when the kitchen is very quiet – but a deeper PULSING HUM everywhere inside the house!

    • Admin says:

      Thank you for taking the time to tell us about your situation. We will continue our fight to get this form of ‘noise’ pollution recognised.

      • Les Howarth says:

        Are there any organisations/scientists/groups involved in INFRASOUND noise pollution to help prove the source of our problem (Hyndburn Wind Farm, Lancashire) … using acoustic equipment? I have no physical evidence to support our case which is needed for this matter to be taken seriously. Thank you.

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