Resource Library Category: Noise (289 items)
Also see NWW press release on noise
Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. This resource library is provided to assist anyone wishing to research the issue of industrial wind power and the impacts of its development. The information should be evaluated by each reader to come to their own conclusions about the many areas of debate.
On Wind Turbine Noise and Air Pressure Pulses
Source: Post, Willem
The von Trapp family came to Vermont because it reminded them of Austria, where “the hills are alive with the sounds of music”. Those sounds will soon be replaced by the health-damaging infrasound and low frequency noise from 3 MW wind turbines on 2,000-ft high ridge lines, courtesy of GMP/Gaz-Metro-Canada.
GMP’s 21 wind turbines of the Lowell Mountain facility will emit various noises, such as:
- machinery noise in the nacelle
- rhythmic/pulsating, trailing-edge noise from the blades (“blade swish”) as they slice through the air at up to 200 mph- irregular, low frequency noise (LFN) and infrasound from the blades due to in-flow air turbulence
- LFN and infrasound at the blade-tower-passage frequency and its harmonics.
Infrasound consists of air pressure pulsations, less than 20 Hz; not audible, but felt; usually not measured by acoustics engineers; more or less ignored by state regulators and state noise codes, mainly because wind energy promoters (vendors, project developers, financial types with tax-shelter schemes for the top 1% of households, legislators getting “campaign” contributions, etc.) have been saying wind energy is “clean and green” and LFN and infrasound are a non-issue.
At 350 m (1,148 ft) from a utility-scale wind turbine, the audible sound emitted by:
- a well-behaving wind turbine with no in-flow turbulence and low wind shear is about 35 dB(A); often during daytime when the sun is warming the ground and air.
- a badly-behaving wind turbine with in-flow turbulence and/or high wind shear is up to 55 dB(A); often during nighttime when a stable atmosphere forms.
This compares with rural nighttime noise of 20-40 dB(A) and urban residential nighttime noise of 58-62 dB(A).
The wind speeds and directions upstream of a wind turbine vary due to terrain effects, such as hilliness and ridge lines, objects on the surface of the terrain, such as buildings and trees, daytime thermal effects and upwind wind turbines.
During daytime, as the 3-bladed rotor turns, it encounters air at various speeds and directions which produces a combination of sound effects, i.e., rhythmic/pulsating blade swish about 3 dB(A) above the steady aerodynamic noise, and a steady rhythm of LFN and infrasound.
Note: Doubling the sound power, watt, increases the sound power level by 3 dB. Doubling the sound pressure, micropascal, increases the sound pressure level, SPL, by 6 dB.
For example: If at 800 uPa (micropascal) the SPL = 20 log (800/20) = 32 dB, at 1600 uPa it is 38 dB, and at 3200 uPa it is 44 dB.
www.osha.gov/dts/osta/otm/noise/health_effects/soundpropagation.htm
During nighttime, air speeds and directions, not influenced by daytime thermal effects, become more varied, the atmosphere becomes more stratified and background noise is less causing the various sound effects (aerodynamic noise, rhythmic/pulsating noises, rhythmic LFN and infrasound) to be noticeably more intense than during the daytime. The daytime blade swish noise often becomes a nighttime clapping, beating, or thumping noise. As the 3-bladed rotor turns at 15 to 20 rpm at greater wind speeds, a blade reaches the top about 45 to 60 times per minute, or 0.75 to 1.0 Hz. At lesser wind speeds the frequencies are less.
The infrasound has audible components (20 to 500 Hz with peak amplitudes at about 200 to 500 Hz) and inaudible components (0 to 20 Hz with peak amplitudes at about 0.75 to 1.0 Hz). The infrasound travels great distances, a mile of more, for large, utility-size wind turbines.
The wind speeds and directions downstream of a wind turbine are similar to the vortices leaving the ends of airplane wings, except they all rotate in the same direction. When the wind direction aligns with the ridge direction of the wind turbines, the downwind turbines will have a degraded performance of up to 20 to 30 percent, i.e., a reduced CF, due to wake turbulence, and they will be noisier, and they will have increased wear and tear.
www.noaanews.noaa.gov/stories2011/20110426_windwakes.html
oto2.wustl.edu/cochlea/wt1.html
Government Noise Codes
Traditionally, state and local government codes dealt mostly with measured sound values that are weighed (adjusted) using the A scale which covers most of the audible frequencies. The A scale corrects dB measurements according to the sensitivity of human hearing. It should not be used for frequencies less than 200 HZ, as the low frequency noise (LFN) and infrasound would be “weighed” out.
The following scales should be used to properly weigh all frequencies, especially those less than 20 Hz that are emitted by wind turbines:
- Most audible noises in the range of 200-20,000 Hz; dB weighed with the A scale, dB(A).
- LFN, in the range of 20-200 Hz; dB weighed with the C scale, dB(C).
- Infrasound less than 20 Hz; dB weighed with the G scale, dB(G). (The instrumentation to quantify infrasound frequencies and amplitudes is expensive and the values obtained vary with the method and instruments used. Applying the G scale to such values may not be meaningful.)
The human ear can hear LFN at 95 dB(G) levels, the inner ear is sensitive to LFN at 65 dB(G) levels. Audible thresholds for perception, ToP, of 95 dB(G) represent the median response to a steady pure tone in a laboratory environment.
If a person is more sensitive to LFN and infrasound, say at the 10% boundary, the ToP may be as low as 85 dB(G) for a steady pure tone. The ToP will also be lower with multiple tones between 0 and 100 Hz that rapidly modulate in amplitude and frequency, as with wind turbine noise.
oto2.wustl.edu/cochlea/windmill.html
Professional acoustical engineers know the government codes, the outcome government regulators are expected to hear and conduct their tests according to standard procedures using mostly the A scale. Wind turbine vendors report sound levels adjusted to the A scale and everyone is satisfied. The LFN and infrasound are usually not covered by government codes.
According to the US EPA, noise levels above 45 dB(A) disturb sleep and most people cannot sleep at noise levels above 70 dB(A).
In Massachusetts, noise is considered pollution if it exceeds the ambient noise level by 10 dB(A). The Department of Environmental Protection, MassDEP, measures noise levels at the complainant’s location and at other nearby locations that may be affected, such as residences and/or buildings with other sensitive receptors. If the noise level at a sensitive receptor’s location is more than 10 dB(A) above ambient, MassDEP requires the noise source to mitigate its impact. The LFN and infrasound are not covered.
www.mass.gov/dep/air/laws/noisepol.htm
In Michigan, the Centerville Township, after 4 years of study, developed and approved a zoning ordinance for commercial wind energy systems. It is strict and comprehensive and should serve as a model for other government entities.
Audible Noise Standard
From 6:00 a.m. until 10:00 p.m., for wind speeds from cut-in to rated-output of the wind turbine facility, the noise level due to the wind turbine facility at the property line closest and at locations within 1 mile of the wind turbine facility shall not exceed the greater of 35 dB(A), or the established outdoor background sound level by more than 5 dB(A).
From 10:00 p.m. until 6:00 a.m., the noise level due to the wind turbine facility at the property line closest and at locations within 1 mile of the wind turbine facility shall not exceed the established outdoor background sound level by more than 3 dB(A). Background sound level shall be established separately for daytime (6:00 a.m.–10:00 p.m.) and for nighttime (10:00 p.m.–6:00 a.m.) values.
LFN or Infrasound
No LFN or infrasound from wind turbine facility operations shall be created which causes the noise level both within the project boundary and a 1 mile radius beyond the project boundary to exceed the following limits:
| Octave Band Center Frequency, Hz | Sound Pressure Level (dB-SPL) | |
| 1-2 | 70 | |
| 16 | 60 | |
| 31.5 | 65 | |
| 63 | 57 | |
| 125 | 50 | |
| 250 | 47 |
Tonality and/or Repetitive, Impulsive Tone Penalty
In the event the audible noise due to wind turbine facility operations exhibits tonality, contains a pure tone and/or repetitive, impulsive noise, the Audible Noise Standard shall be reduced by a total of 5 dB(A).
www.michigan.gov/documents/mdcd/Centerville_Zoning_Ordinance_358577_7.pdf
In Maine, codes require noise levels not to exceed the one-hour average daytime limit (between 7 a.m. and 7 p.m.) of 55 dB(A), and one-hour nighttime limit (between 7 p.m. and 7 a.m.) of 42 dB(A), as measured within 500 feet from a residence, seasonal camp or business at “protected locations”, and 55 dB(A) 24 hours of the day at greater than 500 feet from a residence, seasonal camp or business at “protected locations”, and 75 dB(A) at the wind turbine project boundary. The LFN and infrasound are not covered.
www.maine.gov/dep/ftp/bep/ch375citizen_petition/pre-hearing/AR-83%20-%20Dora%20Mills%20testimony.pdf
Maine Department of Environmental Protection 06-096 CMR c. 375.10.
www.maine.gov/tools/whatsnew/attach.php?id=347543&an=2
Till now, 32 Maine towns have passed their own wind facility ordinances that are stricter than the state ordinance, because they do not trust the state to protect the public safety, health, property values and welfare of the people. This site provides the URLs of the text of the wind ordinances of 12 Maine towns. Vermont towns should get copies of them and use them as a guide to write their own ordinances before it is too late.
In Vermont, codes require nighttime noise levels not to exceed 40 dB(A) as measured at the exterior of a dwelling facade and averaged over a 12-month exposure, the same as the recommendations of the 2009 World Health Organization report that mostly cover road noise, air traffic, and community noise and do not mention wind turbine noise. LFN and infrasound are not covered. The Vermont code does not protect the public health, safety and welfare; it is a wind turbine vendor’s dream come true.
dB values should be measured “at the property line” to ensure people can enjoy their entire property and should not be “averaged over a 12-month period” which would average higher noise levels at higher wind speeds occurring mostly during nighttimes with lower noise levels at lower wind speeds occurring mostly during daytimes.
www.maine.gov/dhhs/mecdc/environmental-health/documents/Vermont-Wind-Turbine.pdf
energizevermont.org/wp-content/uploads/2010/11/2010-11-22_Lovko_Rebuttal_TestimonyDocket7628.pdf
Wind Turbine Noise Annoyance
On an annoyance scale that is based on interviews of people who live near wind turbines, airports, railroads and highways, wind turbine noise is much more annoying at less than 40 dB(A), than the noise from aircraft, highway and rail traffic at less than 70 dB(A).
This additional annoyance is due to the LFN and infrasound emitted by wind turbines. The measured wind turbine noise appears to be benign and within code, but the annoying/unhealthy LFN and infrasound were filtered out by the A scale weighing.
Health Impacts
At less than 20 Hz (infrasound) and above 20,000 Hz (ultrasound) most people do not “hear” noise, but a person’s ears and body are sensitive to infrasound which cause nausea, headaches, insomnia, elevated blood pressure, palpitations, tinnitus, imbalance, dizziness, lack of concentration, moodiness, irritability, anxiety, etc., in SOME people who live about 1/2 mile or less from large, say 1.0 MW, utility-size wind turbines. Infrasound also has potential to harm wildlife and livestock. Little is known about the issue. But there is anecdotal evidence indicating problems. These symptoms are collectively known as “Wind Turbine Syndrome”.
These symptoms occur because the natural frequencies of the internal human and animal organs are in the same frequency range, i.e., 4 to 8 Hz, as those of house walls and floors. Floor resonance can cause the internal organs of the occupants to resonate resulting in an uneasy, irritating feeling. The infrasound is often amplified indoors due to resonating of house walls and floors.
Most peoples’ heart beat is less than 1.25 Hz, or a 75 pulse rate. People who live close to large wind turbines in Falmouth, MA, Ontario, Australia, etc., have complained about feeling internal pressures and having heart troubles and other symptoms which they did not have before the wind turbines were installed.
The symptoms mostly disappear after people move away and reappear after they move back. After many complaints over a long period of time, the Falmouth ruling council finally slowed down the wind turbines at greater wind speeds by partially feathering the blades.
Larger Wind Turbines, Stronger Vibrations
The symptoms studied up till now typically are from exposure to the LFN and infrasound from smaller wind turbines, say up to 2 MW, with 290 ft diameter rotors, as on Lempster Mountain, NH.
The 3 MW Lowell Mountain wind turbines, with 367.5 ft diameter rotors, on 275.6 ft masts, on 2,600 ft high ridge lines, will have greater impacts over larger areas. See website.
www.wind-watch.org/documents/low-frequency-noise-from-large-wind-turbines-2/
The relative amount of LFN is greater for large turbines (2.3–3.6 MW) than for small turbines (less than 2 MW), i.e., the noise from larger wind turbines affects a larger area than from smaller wind turbines. The difference is statistically significant for one-third-octave bands in the frequency range 63–250 Hz.
During the day, ambient audible noise (background noise) in rural areas is much greater than at night, whereas, because of greater nighttime wind speeds, the wind turbine noise is greater at night than during the day. The result is rural people notice audible wind turbine noise much more at night than during the day. Wind turbine promoters arrange field trips for legislators and the public during the day from May-September when wind speeds and noise are minimal.
Dealing With Complaints
Many people living near wind turbines complain about sleep-disturbing nighttime noises that upset their lives to such an extent that their houses are bought by wind turbine owners after they sign gag orders.
As more and larger wind turbines are built near where people work, study, play, etc., the complaints will just multiply, until political pressures restrict the siting of wind turbine projects without suitable buffer zones, or require siting them offshore.
Dismissing the effects as mostly psychological and saying the physical effects are due to something else is not an option; there are just too many people, in too many geographical areas, living too near large wind turbines, with too many complaints. It is better to deal with the problem.
One way to deal with it is to have sufficient distance between people’s houses and utility-scale wind turbines to ensure people are not disturbed by noise and infrasound. Various studies show people living in flat terrain with wind turbines should be at least 1.25 miles (2 km) from such wind turbines. People living in mountainous terrain with wind turbines on ridge lines should be at least 2 miles (3.2 km) from such wind turbines. Such distance standards are becoming more prevalent in Europe, Australia, etc.
Professional acoustical engineers Rick James and George Kamperman have extensively studied wind turbine noise. They recommend a noise limit AT THE PROPERTY LINE for:- Audible noise: 35 dB(A) or no more than 5 dB(A) above the pre-construction ambient dB(A) level, whichever is lower- LFN: 50 dB(C) or no more than 20 dB(C) above the pre-construction ambient dB(C) level, whichever is lower
docs.wind-watch.org/simple-guidelines-for-siting-wind-turbines-to-prevent-health-risks.pdf
Vestas is concerned its 3 MW turbine will not meet stricter noise codes and has actively opposed noise code changes in Denmark, because it fears such changes will set a precedent for changing noise codes throughout the world, thereby adversely affecting 3 MW turbine sales. Other wind energy promoters are also actively opposing noise code changes.
After numerous complaints from people near wind turbine facilities, the Maine Board of Environmental Protection has finally adopted by a 5-4 vote new rules that lower the maximum allowable sound levels emitted by wind farms from 45 dB(A) to 42 dB(A), between 7 p.m. and 7 a.m., as measured from houses and other “protected locations” within one mile of the turbines; a good step in the right direction, but inadequate for rural settings.
Vermont state officials are rushing to have as many ridge line wind facilities built as possible before various federal subsidies expire.
Because of this rushing, they have not heeded, or played down, or dismissed, the environmental concerns of professional testifiers and the complaints from people who live near the Lowell Mountain wind turbine facility. They likely will also not heed the complaints from the fauna and flora currently inhabiting this pristine ridge line.
Because of them, Vermonters are in danger of losing an international reputation of being preservers of their environment and in danger of losing a part of their soul.
By means of various rigged polls to provide CYA for legislators and by means of PR campaigns by wind energy promoters, including foreign companies selling wind turbines, Vermonters were swayed/bamboozled to be in favor of “clean and green” wind energy on ridge lines. However, after they saw the environmental destruction on the 2,600 ft-high Lowell Mountain ridge line, they quickly sobered up.
What makes wind energy even less attractive is that some recent studies show CO2 emission reductions due to wind energy are not anywhere near to what is claimed by promoters. These studies are based on 1/4-hour and 1-hour grid operations data.
Because wind energy is variable and intermittent, it requires backup by quick-ramping, open cycle gas turbine generators that ramp up when wind energy ebbs and ramp down when wind energy surges which occurs at least 100 times per day. Such part-load-ramping operation is inefficient and requires extra fuel/kWh and emits extra CO2/kWh. The extras mostly offset what wind energy was meant to reduce, as proven by analysis of the Eirgrid, Texas and Colorado grid operations data.
theenergycollective.com/willem-post/64492/wind-energy-reduces-co2-emissions-few-percent
www.clepair.net/IerlandUdo.html
docs.wind-watch.org/BENTEK-How-Less-Became-More.pdf
www.clepair.net/windSchiphol.html
www.clepair.net/Udo-okt-e.html
www.clepair.net/Udo-curtail201205.html
Vermonters may want renewable energy, but NOT AT ANY COST, and they certainly do not like to be rushed, forever ruin parts of their state, to beat arbitrary subsidy deadlines for RE projects that will quickly enrich the politically-well-connected top 1% of households at the expense of already-struggling households and businesses in a nearly zero-growth economy.
theenergycollective.com/willem-post/77343/vermont-leaders-back-away-renewable-energy-goals
References
saveourseashore.org/?tag=problems&paged=5
www.amherstislandwindinfo.com/pierpontpaper1.pdf
www.savewesternny.org/docs/pierpont_testimony.html
www.wind-watch.org/documents/public-health-impacts-of-wind-turbines/
stopturbinesincushnie.com/Letters/WTS.pdf
www.governing.com/topics/energy-env/Are-Wind-Farms-a.html
www.nytimes.com/2010/10/06/business/energy-environment/06noise.html
www.windaction.org/documents/10358
www.windturbinesyndrome.com/news/2011/government-caught-lying-about-wts-ontario/
saveourseashore.org/?cat=35&paged=2
www.nytimes.com/2010/10/06/business/energy-environment/06noise.html
www.maine.gov/doc/mfs/windpower/pubs/pdf/AddressingWindTurbineNoise.pdf
randacoustics.com/wp-content/uploads/2011/12/The-Bruce-McPherson-ILFN-Study.pdf
[via theenergycollective.com]
Attended Sampling of Sound from Wind Turbine 1, Falmouth, MA
Source: Mass. Department of Environmental Protection
Executive Summary
This report presents the results of attended sound sampling of Falmouth’s Wind Turbine #1 located at the Waste Water Treatment Facility on Service Road in East Falmouth. In September, 2011 the town of Falmouth requested the Department of Environmental Protection (MassDEP) to conduct sound sampling of Falmouth’s Wind #1 turbine in response to numerous noise complaints from neighbors. This sampling augments the unattended sound study conducted by the Town’s consultants in the summer of 2010.
In order to quantify the impact of the turbine under the worst-case scenario operating· conditions, MassDEP technicians took samples from five separate residential locations during nighttime hours (when ambient noise is quietest). The sampling protocol was designed to try to capture sound for the “worst case” conditions in the area of Wind #1 while monitoring sound that could be directly attributable to Wind #1. This approach is typical of what MassDEP .does when conducting a sound survey for purposes of determining compliance with the MassDEP noise policy.
Over the course of four nights, MassDEP conducted sound sampling with Wind #1 operational at five residential locations close to the wind turbine. Data was also collected for background sound without turbine operations. Because the sampling was attended, the study was able to focus directly on sound from the wind turbine without interference from other sound sources.
The results of the field sampling indicate that Wind #1 exceeds 10 decibels above background sound levels during nighttime hours, which is the limit above which MassDEP considers a noise a nuisance regulated by MassDEP’s noise regulation (31 0 CMR 7.1 0) and MassDEP’s noise policy. The noise exceedance was found at one location under both high and low wind conditions.
Based upon the same sampling data, this report indicates that octave band analysis for pure tone is inconclusive.
Attended Sampling of Sound from Wind Turbine #1, Falmouth, MA
Wind Turbine Acoustic Pollution Assessment Requirements
Source: Waubra Foundation
On behalf of the many people around the world, suffering acute and chronic health damage from living near wind turbines, the Waubra Foundation demands that relevant authorities initiate:
- full frequency spectrum acoustic monitoring inside and outside the homes and workplaces of people claiming health problems caused by the proximity of operating wind turbines;
- the monitoring must be conducted for sufficient time, under the weather and wind conditions indicated by victims as being contributive to their symptoms;
- measurements must specifically include, infrasound and low frequency noise, (dBZ or dBLin, dBA, dBC, & dBG).
The noise monitoring must be performed by accredited acousticians demonstrably independent of the wind industry, approved by the sufferers, and in a manner that will avoid any deliberate manipulation of turbine operation to reduce the acoustic emissions during testing. The results (including all the raw data and associated sound files) must be made available to all parties.
The Rationale for These Demands
- Most health practitioners are well aware of the links between chronic severe sleep deprivation (1) chronic stress (2) and poor physical and mental health. This is exactly what residents living near wind turbines are experiencing, (3) together with other specific symptoms directly correlating with acute exposure to this sound energy (4,5,6,7).
- Knowledge of the damage to health from exposure to infrasound (8) and low frequency noise (9) (ILFN) has been known for many years. Despite this, little is known about the current exposure levels of residents to ILFN emissions from wind turbines inside their homes.
- The link between chronic exposure to low frequency noise and chronic physiological stress, even when asleep, was clearly highlighted by Professor Leventhall et al in 2003 (10).
- Most medical practitioners have been unaware of the problems associated with exposure to ILFN. This ignorance has not been helped by acousticians and others calling such problems “annoyance” without accurate clinical diagnoses (11).
- These symptoms have been reported to occur specifically with exposure to operating wind turbines by medical practitioners since 2003 (12,13,14,15,16,17). Symptoms have been reported by acousticians, health practitioners and residents from countries including Denmark, Sweden, Germany, United Kingdom, France, United States, Canada, New Zealand and Australia.
- Symptoms have been reported historically up to 4km from the nearest wind turbine, and more recently characteristic symptom patterns have been reported at distances up 10km away from the nearest wind turbine (18). This is described especially with larger wind turbines (eg 3MW), and on occasions even further away, where turbines are sited at altitude (19) or near expanses of water.
- These health problems consistently worsen over time, until the exposure ceases. Families are being advised by their treating doctors to leave their homes in order to regain their health. Many have nowhere else to go, and cannot sell their homes, so they become homeless “wind farm refugees”. Others remain trapped, unable to move (20).
- Professors Moller and Pedersen, from the University of Aalborg in Denmark, have confirmed that larger more powerful wind turbines emit more low frequency sound waves as a proportion of their sound emissions (21). These emissions are known to easily penetrate through the walls, roofs, and windows of homes and workplaces, due to the lower transmission loss of low frequencies.
- Recent acoustic survey work in the USA (Falmouth) (22) and Australia (NSW) (23) has confirmed that low frequency noise and pulsatile infrasound emitted by wind turbines have been measured inside the homes and workplaces of sick people, and occur when they are experiencing the symptoms of Wind Turbine Syndrome.
- Currently governments around the world do not require measurement of the full sound and vibration spectrum, do not require measurement inside homes and workplaces, do not require evaluation of sleep or other disturbances, but instead limit almost all assessment to audible noise (dBA) only, outside homes and workplaces.
Summary
The plight of people made ill by wind turbine acoustic pollution has been universally ignored by their respective governments.
The current noise assessment practices and standards are incompetent and unacceptable, and must be changed to include full spectrum acoustic monitoring inside homes and workplaces as a matter of urgency.
References
1. Capuccio F et al, “Sleep duration predicts cardiovascular outcomes:a systemic review and meta-analysis of prospective studies” European Heart Journal, 2011, 32:1484-1492
2. McEwen, Bruce, “Protective and Damaging Effects of Stress Mediators” NEJM 1998, 338:171-179
3. Shepherd, Daniel et al, “Evaluating the impact of wind turbine noise on health-related quality of life” Noise & Health, September-October 2011, 13:54,333-9 www.wind-watch.org/documents/evaluating-the-impact-of-wind-turbine-noise-on-health-related-quality-of-life
4. Pierpont, Dr Nina, “Wind Turbine Syndrome, A Report on a Natural Experiment” Published by K Selected Books, Santa Fe NM 2009 www.windturbinesyndrome.com see also www.wind-watch.org/documents/wind-turbine-syndrome-excerpts-from-the-executive-summary
5. McMurtry, Professor Robert, “Toward a Case Definition of Adverse Health Effects in the Environs of Industrial Wind Turbines: Facilitating a Clinical Diagnosis” Bulletin of Science Technology and Society 2011 31:316 http://bst.sagepub.com/content/31/4/316
6. Phillips, Prof Carl V, “Properly interpreting the epidemiological evidence about the health effects of industrial wind turbines on nearby residents” Bulletin of Science, Technology and Society vol 31 No 4 (August 2011) pp 303–315 http://www.wind-watch.org/documents/properly-interpreting-the-epidemiologic-evidence-about-the-health-effects-of-industrial-wind-turbines-on-nearby-residents/
7. Leventhall, Benton & Pelmear, May 2003, A report for DEFRA “A review of published Research on Low Frequency Noise and its Effects” http://archive.defra.gov.uk/environment/quality/noise/research/lowfrequency/
8. NIEHS (National Institute of Environmental Health Sciences), November 2001, “Infrasound Brief Review of Toxicological Literature”
9. Leventhall, Benton & Pelmear, May 2003 op cit
10. Leventhall, Benton & Pelmear, May 2003 op cit Section 10
11. Pederson & Waye, “Perception and Annoyance due to wind turbine noise – a dose-response relationship” in J Acoustical Society America 116 (6) 2004 pp 3460-70
12. Harry, Dr Amanda, “Wind turbines, Noise and Health” 2007 www.wind-watch.org/documents/wind-turbines-noise-and-health
13. Iser, Dr David, personal communication
14. Pierpont, Dr Nina, “Wind Turbine Syndrome, A Report on a Natural Experiment” Published by K Selected Books, Santa Fe NM 2009 www.windturbinesyndrome.com
15. McMurtry, Professor Robert, “Toward a Case Definition of Adverse Health Effects in the Environs of Industrial Wind Turbines: Facilitating a Clinical Diagnosis” Bulletin of Science Technology and Society 2011 31:316 http://bst.sagepub.com/content/31/4/316
16. Hanning C & Evans A, BMJ 2012:344e1527 www.wind-watch.org/documents/wind-turbine-noise-editorial
17. Laurie, Dr Sarah, Medical Director, Waubra Foundation, Submission to the Australian Federal Senate Inquiry into Rural wind Farms, February 2011, accessible via www.waubrafoundation.com.au
18. Waubra Foundation Submission to the NSW Department of Planning, March 2012, at www.wind-watch.org/documents/response-to-nsw-planning-department-draft-guidelines-for-wind-developments
19. Personal communication, Hubert De Bonneville, see also www.windturbinesyndrome.com/2012/french-writer-going-nuts-from-wind-turbines-france
20. www.wind-watch.org/news/2012/03/09/letter-to-australian-prime-minister-from-dr-sarah-laurie
21. Moller & Pedersen “Low Frequency Noise from Large Turbines” J Acoustical Society America 2011 129:3727–3744 www.wind-watch.org/documents/low-frequency-noise-from-large-wind-turbines-2
22. Ambrose, Stephen & Rand, Robert “Bruce McPherson Infrasound and Low Frequency Noise Study” 2011 www.wind-watch.org/documents/bruce- mcpherson-infrasound-and-low-frequency-noise-study
23. Cooper, Steven “Review of Draft NSW Guidelines” March 2012 www.wind-watch.org/documents/review-of-nsw-draft-wind-farm-guidelines
The Waubra Foundation
11th May, 2012
Download original document: “Wind Turbine Acoustic Pollution Assessment Requirements”
Assessment of low-frequency noise from wind turbines in Maastricht
Source: Møller, Henrik; Pedersen, Steffen; Kloster Staunstsrup, Jan; and Sejer Pedersen, Christian
Introduction
Sound and noise can be characterized by their frequency. The range from 20 Hz to 20 kHz (20 cycles per second to 20,000 cycles per second) is usually called the normal hearing range or the audio frequency range. Sound with frequencies above 20 kHz is denoted ultrasound and cannot be heard by humans.
Sound with frequencies below 20 Hz is denoted infrasound. It is usually understood that also infrasound cannot be heard, but this is wrong. Infrasound is audible at least down to 1 or 2 Hz, provided that the sound pressure level is sufficiently high. The sound is perceived with the ears, usually giving a feeling of pressure at the eardrums.
The 20‐200 Hz range is denoted the low‐frequency range. Slightly different limits are sometimes used, e.g. 10‐160 Hz. …
Low‐frequency wind turbine noise is usually described as humming or rumbling. It may have a more or less pronounced tonal character, e.g. in terms of tones that fluctuate and vary in level and/or pitch, or of tone‐ like pulses excited with regular or random intervals. The feeling of pressure at the eardrums is also reported. It is characteristic that the noise varies a lot in time and with wind and other atmospheric conditions.
The rate of modulation of the low‐frequency noise from wind turbines (and higher frequencies as well) is often in the infrasonic frequency range, e.g. the blade passage frequency, and the noise may thus be mistaken as infrasound, even when there is little or virtually no infrasound present.
What are the main effects of low-frequency noise (LFN) on humans and when specifically do these effects occur?
Noise with prominent low‐frequency components may affect human health and well‐being to a larger extent than noise without such components.
At low frequencies, the loudness increases more steeply above the hearing threshold than at higher frequencies. Thus, a sound moderately above threshold may be perceived not only loud but also annoying. Since there is a natural spread in hearing thresholds between individuals, a low‐frequency sound that is inaudible or soft to some people may be loud and annoying to others.
Low‐frequency sound is particularly annoying, when it occurs alone or with low levels of sound at higher frequencies. This means that it is usually more annoying indoors than outdoors, since the high frequencies are more attenuated by the sound insulation of the house than the low frequencies are. Also it is often more annoying in the evening and at night, when it is otherwise quiet.
Prolonged exposure to audible low‐frequency sound may cause fatigue, headache, impaired concentration, sleep disturbance and physiological stress as indicated by increased levels of saliva cortisol.
The Danish Government has changed the regulations for erecting wind turbines as a result of your research. Is that correct? And if so, what specific changes have been made?
Low‐frequency limit
The general (i.e. not for wind turbines) Danish limit for low‐frequency noise in dwellings is an indoor A‐ weighted sound pressure level of 20 dB (evening and night) and 25 dB (day). Only frequencies in the 10‐160 Hz frequency range (third‐octave frequencies) are included. … Unlike for other noise sources, the low‐frequency noise is not measured but calculated from measurements close to the turbine of the emitted sound. … This need not be a problem, if the calculations are correct. But they are not. … The issue is that sound at low frequencies varies within a room – usually by many decibels – and … the level should – briefly explained – be measured where the annoyed person finds it loudest. The sound insulation must be measured the same way in order to be applicable for calculations of relevant indoor levels from outdoor levels. But it was not. The indoor measurements were simply made at arbitrary positions that were not selected for a high level. Thus the obtained values of sound insulation are too high.
Figure 1 shows an example of the sound distribution in a room. Each frame shows the sound distribution in a given height, and the color scale gives the sound pressure level (scale at the right).
As a result, the calculation of the Danish regulation gives values that underestimate the low‐frequency noise that would be measured in neighboring houses. The magnitude of the error is estimated to be around 5 dB.
Even when an error of 5 dB might seem small, it is far from being negligible. … The loudness and annoyance increase more steeply above threshold than at higher frequencies. This means that when the level is a few decibels above the 20 dB limit, the consequences are more severe, than if a limit at higher frequencies is exceeded by the same amount. Most people will hear a sound at 20 dB, and some will find it annoying. Few people would probably accept 25 dB in their home at night and hardly anyone would accept 30 dB. …
Is it possible to indicate the expected LFN that will be produced by the planned four wind turbines of type Vestas V112 3MW, hub height 119 m?
Because of differences in sound insulation, not all houses will have the same indoor noise, and higher sound pressure levels than calculated will be observed in some houses. It is the expressed objective of the Danish regulation that higher levels will be observed in 33% of the houses. Hoffmeyer and Jakobsen had otherwise proposed that the calculated level should only be exceeded in 10‐20% of the houses. In the following, calculations have also been made with their proposed sound insulation data (results likewise corrected by the estimated 5‐dB measurement error). …
It is seen that the 20‐dB limit will be exceeded in a very large area with many dwellings and not only at the nearest neighbors. It should be remembered that the loudness increases more steeply above the hearing threshold than at higher frequencies, and that “The perceived annoyance from low frequency noise increases strongly when the noise reaches above 20 dB” (quote from Danish EPA).
General comments to the project
Total noise outdoors
The Dutch noise limits for wind turbine noise45,46 are based on the day‐evening‐night concept, Lden, the long‐term (yearly) equivalent level, where noise in the evening is given a penalty of 5 dB and noise in the night a penalty of 10 dB. This concept was developed to allow traffic noise with a typical 24‐hour pattern to be characterized by a single figure. However, such diurnal pattern does not exist for wind turbines, since wind turbines run around the clock, and we do not find it suitable to characterize wind turbine noise by Lden. Also Pedersen argued against using of Lden for wind turbine noise.
Since most complaints relate to the wind turbine noise in the evening and at night, we appreciate that there is an additional Dutch limit for the level at night Lnight. However, this limit also applies to a yearly average, which allows more noise at some nights, if there is less noise at other nights. This is not the way the human organism works, though. If we are disturbed by noise in the night, we cannot take advantage of the fact that, after a while – tomorrow, after some days, maybe a week – there will be nights with less or no noise. It is our conviction that limits should apply to the actual noise in situations that occur regularly.
Prepared for the City Council of Maastricht, 10 April 2012.
By Henrik Møller,* Steffen Pedersen,* Jan Kloster Staunstrup,† and Christian Sejer Pedersen*
*Section of Acoustics, †Department of Development and Planning, Aalborg University, Denmark
Download original document: “Assessment of low‐frequency noise from wind turbines in Maastricht”
