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Resource Documents: Noise (514 items)

RSSNoise

Also see NWW press release on noise

Documents presented here are not the product of nor are they necessarily endorsed by National Wind Watch. These resource documents are 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.


Date added:  November 5, 2014
Health, NoisePrint storyE-mail story

Negative health effects of noise from industrial wind turbines: Some background

Author:  Punch, Jerry; and James, Richard

This post, the first of a three-part series, provides a broad overview of the topic. The second installment will review the major research findings linking low-frequency noise and infrasound from industrial wind turbines with effects on health and quality of life. Part three will discuss the relationship between various health effects and the processing of infrasound by the ear and brain.[1] [Part 2: The Evidence; Part 3: How the Ear and Brain Process infrasound]

Cary Shineldecker was skeptical about the wind project the Mason County, Michigan, planning commission was considering for approval. His home, two miles from Lake Michigan, was located in an area where nighttime noise levels were around 25 dBA, with only occasional traffic and seasonal farmland noises. The rolling hills, woodlots, orchards, fields, and meadows surrounding his property contributed to its peaceful country setting. He voiced his skepticism about the wind turbines repeatedly in community meetings held before Consumers Energy was finally granted approval to construct 56 476-foot turbines, one that would be 1,139 feet from his property line (Figure 1), six within 3,000 feet, and 26 close enough to be visible from his property.

Figure 1 - An industrial-scale wind turbine during installation near the Shineldecker home in Mason County, Michigan.

Figure 1 – An industrial-scale wind turbine during installation near the Shineldecker home in Mason County, Michigan.

Cary and his wife, Karen, started to suffer symptoms of ear pressure, severe headaches, anxiety, irritability, sleep disturbance, memory loss, fatigue, and depression immediately after the turbines began operating.

Gradually, as sleep disturbance turned into sleep deprivation, they felt their home was being transformed from a sanctuary to a prison. Deciding to sell their home of 20 years, they put it on the market in March 2011, and it has remained unsold for 3-1/2 years. For the past year and a half, their nightly ritual has been taking sleeping medications and retreating into their basement to try to sleep on a corner mattress.

The Shineldeckers received few offers to buy their home, and recently accepted an offer that would mean a substantial financial loss. They are scheduled to go to trial against Consumers Energy, and if their case goes to settlement without a trial, they will likely be forced into a confidentiality agreement about their case.

MANY SUCH COMPLAINTS

Similar complaints of adverse health effects (AHEs) associated with living near utility-scale wind turbines have become commonplace in the U.S. and other developed countries. Energy companies in the U.S., motivated by lucrative tax subsidies available for developing wind resources as a form of “green energy,” are pushing aggressively to install more wind turbines, typically locating them near residential properties. Many rural residents now have one or more industrial machines that stand over 40 stories tall on the property alongside their home. Complaints about noise from people living within the footprint of wind energy projects are very similar to those experienced by the Shineldeckers.

Those who have never visited a wind project or who visit one only during the daytime often leave believing that the complaints of noise are unfounded, and commonly assume them to be psychologically motivated or a form of NIMBYism. Those living near wind turbines say that unless one is willing to spend several nights in the area they have not experienced the noise that causes the complaints.

THE CHANGING RURAL LANDSCAPE

Prior to the installation of the wind turbines, these rural communities were typically very quiet at night, with background sound levels ranging between 20 and 25 dBA. After the turbines began operation, the noise levels jumped to 40 or even 50 dBA, and sometimes higher. It is common for wind turbines to be barely audible during the day, yet be the dominant noise source at night. Environmental sounds are quieter in the evening, lowering the background sound levels, and wind speeds tend to be higher at blade height during nighttime hours, which increases sound emissions. Further, nighttime weather conditions enhance sound propagation. The result is that at night wind turbines can be a significantly more noticeable noise source than during the daytime.

Commercial wind turbine blades produce aerodynamic noise in both the inaudible and audible range, collectively referred to as infrasound and low-frequency noise (ILFN). Although some of the audible noise is above 200 Hz, much of it falls into the low-frequency region around 0-100 Hz. Infrasound, generally considered to be inaudible, encompasses sound energy in the range from 0-20 Hz. It is measurable with either an infrasonic microphone or a microbarometer. The frequency and amplitude of wind turbine noise depend mainly on the blade-rotation speed. Measurements show increased acoustic energy with decreasing frequency, reaching a maximum at frequencies under 1 Hz.

Promoters of wind energy frame it in agricultural terms that portray it as harvesting the wind. This framing leads to the belief that wind farms are a natural fit with agricultural land use.

From this viewpoint, farmers should also be allowed to use their land to harvest the energy of the atom by hosting a small nuclear plant. Hosting a utility-scale wind turbine is not farming; it is operation of a commercial utility. The installation of utility-scale, energy-conversion machines requires strict zoning and regulation, as one would expect for a zoned industrial region. These machines are in no way similar to traditional agricultural equipment. Thus we consider the term industrial to be an accurate description of utility-scale wind turbines.

Wind turbines are often sited in regions where agricultural land use is intermixed with residential land use. A single wind energy utility typically consists of 40 to 60 wind turbines. Forty-five 2-MWatt turbines cover about 36 square miles of land. This requires only 10 to 20 farmers to sign leases for hosting one or more of the turbines, but may put several hundred non-participating farms and residential homes within the risk zone for noise disturbance.

While a few farmers or landowners in the host community benefit financially, many others—often at ratios of 20 to 1 or higher—find that the peace and quiet of evenings and nights that attracted them to the rural community is replaced with the unwanted consequences of audible sounds and inaudible infrasound.

In the final two installments of this three-part series, our goal is to explain the bases for a variety of health complaints that are being associated with the current practice of locating industrial-scale wind turbines as close as 1,200 to 1,500 feet from homes. In areas with a relatively long history of industrial wind turbines (IWTs), a distance of at least 1-1/4 miles (2 kilometers)—and more in areas with hilly terrain—is now considered necessary to avoid negative impacts on health.

Jerry Punch, PhD, is an audiologist and professor emeritus at Michigan State University in the Department of Communicative Sciences and Disorders. Since his retirement in 2011, he has become actively involved as a private audiological consultant in areas related to his long-standing interest in community noise.

Richard James, INCE, BME, is an acoustical consultant with over 40 years of experience in industrial noise measurement and control. He is an adjunct instructor in Michigan State University’s Department of Communicative Sciences and Disorders and an adjunct professor in Central Michigan University’s Department of Communication Disorders.

[1] Interested readers may wish to refer to the article, “Wind-Turbine Noise: What Audiologists Should Know,” published in the July-August 2010 issue of Audiology Today, as a backdrop for this series.

[Originally published at Hearing Health & Technology Matters, Nov. 4, 2014]

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Date added:  November 3, 2014
Health, Noise, Regulations, SafetyPrint storyE-mail story

Noise, flicker, health and safety

Author:  Wiser, Ryan; Yang, Zhenbin; et al.

[section 7.6.3.3 (pp. 575-576), “Wind Energy,” IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation, 2011]

A variety of proximal ‘nuisance’ effects are also sometimes raised with respect to wind energy development, the most prominent of which is noise. Noise from wind turbines can be a problem, especially for those living within close range. Possible impacts can be characterized as both audible and sub-audible (i.e., infrasound). There are claims that sub-audible sound, that is, below the nominal audible frequency range, may cause health effects (Alves-Pereira and Branco, 2007), but a variety of studies (Jakobsen, 2005; Leventhall, 2006) and government reports (e.g., FANM, 2005; MDOH, 2009; CMOH, 2010; NHMRC, 2010) have not found sufficient evidence to support those claims to this point. Regarding audible noise from turbines, environmental noise guidelines (EPA, 1974, 1978; WHO, 1999, 2009) are generally believed to be sufficient to ensure that direct physiological health effects (e.g., hearing loss) are avoided (McCunney and Meyer, 2007). Some nearby residents, however, do experience annoyance from wind turbine sound (Pedersen and Waye, 2007, 2008; Pedersen et al., 2010), which can impact sleep patterns and well-being. This annoyance is correlated with acoustic factors (e.g., sound levels and characteristics) and also with non-acoustic factors (e.g., visibility of, or attitudes towards, the turbines) (Pedersen and Waye, 2007, 2008; Pedersen et al., 2010). Concerns about noise emissions may be especially great when hub-height wind speeds are high, but ground-level speeds are low (i.e., conditions of high wind shear). Under such conditions, the lack of wind-induced background noise at ground level coupled with higher sound levels from the turbines has been linked to increased audibility and in some cases annoyance (van den Berg, 2004, 2005, 2008; Prospathopoulos and Voutsinas, 2005).

Significant efforts have been made to reduce the sound levels emitted by wind turbines. As a result, mechanical sounds from modern turbines (e.g., gearboxes and generators) have been substantially reduced. Aeroacoustic noise is now the dominant concern (Wagner et al., 1996), and some of the specific aeroacoustic characteristics of wind turbines (e.g., van den Berg, 2005) have been found to be particularly detectable (Fastl and Zwicker, 2007) and annoying (Bradley, 1994; Bengtsson et al., 2009). Reducing aeroacoustic noise can be most easily accomplished by reducing blade speed, but different tip shapes and airfoil designs have also been explored (Migliore and Oerlemans, 2004; Lutz et al., 2007). In addition, the predictive models and environmental regulations used to manage these impacts have improved to some degree. Specifically, in some jurisdictions, both the wind shear and maximum sound power levels under all operating conditions are taken into account when establishing regulations (Bastasch et al., 2006). Absolute maximum sound levels during the day (e.g., 55 A-weighted decibels, dBA) and night (e.g., 45 dBA) can also be coupled with maximum levels that are set relative to pre-existing background sound levels (Bastasch et al., 2006). In other jurisdictions, simpler and cruder setbacks mandate a minimum distance between turbines and other structures (MOE, 2009). Despite these efforts, concerns about noise impacts remain a barrier to wind energy deployment in some areas.

In addition to sound impacts, rotating turbine blades can also cast moving shadows (i.e., shadow flicker), which may be annoying to residents living close to wind turbines. Turbines can be sited to minimize these concerns, or the operation of wind turbines can be stopped during acute periods (Hohmeyer et al., 2005). Finally, wind turbines can shed parts of or whole blades as a result of an accident or icing (or more broadly, blades can shed built-up ice, or turbines could collapse entirely). Wind energy technology certification standards are aimed at reducing such accidents (see Section 7.3.2), and setback requirements further reduce the remaining risks. In practice, fatalities and injuries have been rare (see Chapter 9 for a comparison of accident risks among energy generation technologies).

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Date added:  November 2, 2014
Health, NoisePrint storyE-mail story

Significant infrasound levels a previously unrecognized contaminant in landmark motion sickness studies

Author:  Dooley, Kevin

Abstract. Airborne Infrasound at any given point can be accurately described as fluctuations or cyclic changes in the local barometric pressure. Variations in a motion sickness test subject’s elevation, result in fluctuations in the surrounding barometric pressure by a similar amount to that experienced on a ship in high seas. Cyclic variation in the lateral or linear velocity of a subject in a vehicle or platform in atmospheric air may also be subject to infrasonic pressure fluctuations due to the Bernoulli principle and associated with vortex shedding effects. Calculations presented demonstrate that in at least one landmark study (McCauley et al 1976) test subjects were exposed to infrasonic sound pressure levels in excess of 105 dB at discrete frequencies between 0.063 Hz and 0.7Hz. The infrasonic sound pressure level necessarily present in cyclic motion in free atmospheric air does not appear to have been accounted for as a nausea influencing factor in the McCauley et al (1976) motion sickness studies.

Proceedings of Meetings on Acoustics, Vol. 20, 040007 (2014)

Download original document: “Significant infrasound levels a previously unrecognized contaminant in landmark motion sickness studies”

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Date added:  November 2, 2014
Noise, TechnologyPrint storyE-mail story

Acoustic interaction as a primary cause of infrasonic spinning mode generation and propagation from wind turbines

Author:  Dooley, Kevin; and Metelka, Andy

Abstract. Relatively balanced load related pressure waves from the rear surface of each rotor blade, are at a frequency of 1 per revolution of the turbine and are phase shifted by 120 degrees from each other. The superpositions of these infrasonic waves destructively interfere. This action results in a non-propagating rotor locked mode, however, the shielding (reflecting) effect of the tower as each blade passes, interrupts the balanced destructive interference for a small portion of rotor angle three times per revolution. The momentary un-balance between the destructive interfering waves, results in the generation of Tyler-Sofrin spinning mode series, which propagate into the far field. The spinning mode radiation angles, coupled with the low decay rate of infrasound, result in higher far field sound pressure levels than would be predicted for a point source. An analysis approach partially derived from Tyler-Sofrin (1962) is presented. Field microphone data including phase measurements identifying the spinning modes are also presented.

Kevin A. Dooley, Kevin Allan Dooley Inc., Toronto, Ontario, Canada.
Andy Metelka, Sound and Vibrations Solutions Inc., Acton, Ontario, Canada.

The Journal of the Acoustical Society of America 2013; 134: 4097.
doi: 10.1121/1.4830965

Download draft document (Dec. 9, 2013): “Acoustic interaction as a primary cause of infrasonic spinning mode generation and propagation from wind turbines”

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