Resource Documents: Noise (487 items)
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.
Author: Kasprzak, Cezary
[D]ue to the typical size of turbines and their airspace configuration, they can adversely impact the natural environment posing potential hazards such as noise emission, vibrations, non-ionizing radiation effects, emergency situations, the shadow flicker effect, and permanent shade conditions. Turbines may have also a negative effect on the local fauna (particularly birds) as well as the landscape.
In case of wind turbines, both low-frequency noise and audible noise is produced by various aerodynamic noise sources (turbulent layer tearing off from blade edges, boundary layer tearing off, onset of vortex air flows, induction of a boundary vortex, vortices of laminar layer, turbulence of the inflowing air stream) as well as by mechanical noise sources (gearboxes, generators, devices altering the headstock direction, cooling system pumps, ancillary facilities, etc.) .
Despite the fact that modern wind turbines operated at daytime generate far less noise than their prototypes, they still appear to strongly affect people. Under certain weather conditions, this noise is transmitted over large distances and exceeds (by about 10–15 dB) the noise levels obtained from numerical models . In most cases, this effect can only be sensed in a subjective manner which means that the very presence of wind turbines may bring about acoustic or beyond-acoustic annoyance reactions in humans (distraction, irritation). These factors are accounted for in the sound level models and questionnaire tools that were a part of experiments conducted mainly in Holland and Sweden and connected with the level and spectral composition of sound generated by wind turbines emitted over the neighboring areas (residential areas). When addressing the issue, other aspects have to be considered as well: time of the day, atmospheric conditions (wind speed and direction), personal attitude towards wind power generation (ardent supporters and fierce opponents), the actual distance from a wind mill farm or the age of people being interviewed [3–6].
The noise produces negative reactions of the nervous system, affecting such abilities as reading ability, attention, problem solving, and memory. Noise appears to have a negative impact on children at school, mainly because it is impossible to control. It can also lead to elevated levels of stress hormones and increased blood pressure at rest. This unfavorable reaction is stronger in children whose school performance is poor.
Most people do not cope well with the effect of noise exposure, and because of that they run a higher risk of suffering from its harmful effects than it was proved in previous studies [7–9].
In 2001, at the University of Wisconsin–Madison the research workers distributed a questionnaire among the residents who had lived for two years in close proximity of a wind power installation comprising 22 turbines. The results of their investigations showed that 44% of people living within a distance of 243–402 meters from wind turbines estimated the noise level as an important issue in their households. Similar tendency was observed among 52% of residents living 804–1600 meters away from turbines, as well as in the 4% of those residing 1600–3200 meters from the wind farm. Under certain conditions, wind turbines could still be heard from the distance of 3.2 km .
These findings have been confirmed by Van den Berg, doctor of medicine at Groningen University in Holland, located at the Dutch-German border in the vicinity of a modern wind power plant consisting of 17 turbines with total power of 30 MW. Residents who lived 500 m and further from the turbines reacted strongly to noise pollution, while those living in an approximate distance of 1.9 km displayed clear signs of annoyance (anger) .
In 2005, a survey was carried out among 200 people living 1.2 km from a French wind mill farm in St. Crepin. 83% of residents took part in the survey, 27% found the noise level unbearable at night, 58% claimed that noises during nights seriously interfered with their night’s rest, while 10% stated that noise in the course of the day was at least distracting, and that was just a six-turbine installation with the rated power of 9 MW .
According to the Dutch standards, the noise of wind mill turbines is to be measured based on the average level of exposure Lden (day-evening-night) which is defined in correlation with the wind speed value at the height of the tower .
According to Schreurs , as long as the infra frequency noise level is kept below 40 dB(A), the annoying effects should not be acute and the residents’ health should not be strongly affected. For average exposure levels Lden exceeding 45dB(A), the noise is expected to be perceived as irritating and may cause sleep disorders thus affecting human health.
The subjective assessment of sound emitted by wind mill parks was conducted on the basis of surveys collected from residents living nearby wind farms [5, 11]. The issues addressed included verbal evaluation of noise generated by wind turbine elements, subjective perception of this type noise for different wind conditions as well as the impact of non-acoustic factors (economical benefits, wind mill view, living conditions) on the perceptibility and inconvenience resulting from the noise. The results of surveys carried out in Holland, in which respondents were asked to come up with the most accurate term describing sounds generated by wind power plants located at a distance of 2.5 km from their permanent residence, revealed that 80% of respondents described the noise as whistling. This group included both those who sensed certain level of discomfort and respondents who did not complain about the wind mill presence at all . Research efforts aimed at defining the exposure-reaction curve for wind power plants noise both inside and outside houses are summarized in .
The purpose of the experiment presented in this paper was to determine the effect of infrasound waves on variations in Delta, Theta, Alpha, SMR, Beta1, and Beta2 waves in humans exposed to infrasound noise in an attempt to give a more objective evaluation of the impacts of infrasound generated by wind turbines.
Papers [13–18] report a statistically significant change in patterns of EEG and ECG signals in humans. Dominant changes were observed in the alpha rhythm during the infrasound exposure.
 S. Oerlemans, P. Sijtsma, L. Méndez, Location and quantification of noise sources on a wind turbine. J. Sound Vibr. 299, 869 (2007).
 G.P. van den Berg, Effects of the wind profile at night on wind turbine sound. J. Sound Vibr. 277, 955 (2004).
 M.V. Lowson, Aerodynamic noise of wind turbines. Proc. Internoise 96, 479 (1996).
 E. Schreurs, J. Jabben, E. Verhejien, Wind turbine noise in the Netherlands: a modelling and monitoring approach. Proc. Euronoise 2009, 3975 (2009).
 G.P. van den Berg, Why is wind turbine noise noisier than other noise? Proc. Euronoise 2009, 3965 (2009).
 E. Pedersen, G.P. van den Berg, R. Bakker, J. Bouma, Response to noise from modern wind farms in The Netherlands. J. Acoust. Soc. Am. 126, 634 (2009).
 B. Berglund, P. Hassmén, R.F. Soames, Sources and effects of low-frequency noise. J. Acoust. Soc. Am. 5, 2985 (1996).
 M. Alves-Pereira, Noise-induced extra-aural pathology: a review and commentary. Aviat. Space Environ. Med. 70, 7 (1999).
 M. Branco, M. Alves-Pereira, Vibroacoustic Disease. Noise Health 23, 3 (2004).
 D.E. Kabes, C. Smith, Excerpts from the final report of the Township of Lincoln Wind Turbine, Agricultural Resource Center, Madison 2001.
 E. Pedersen, Human response to wind turbine noise &emdash perception, annoyance and moderating factors, Sahlgrenska Academy, Göteborg 2007.
 S.A. Janssen, A.R. Eisses, E. Pedersen, Exposure-response relationships for annoyance by wind turbine noise: a comparison with other stationary sources. Euronoise 2009, 1472 (2009).
 C. Kasprzak, The influence of infrasounds on the electrocardiograph patterns in humans. Acta Phys. Pol. A 118, 87 (2010).
 C. Kasprzak, [Possibility of application of infrasound therapy in treatment of sleep disorders.] Acta Bio-Optica Inform. Med. 15, 390 (2009).
 Z. Damijan, C. Kasprzak, R. Panuszka, Low‐frequency sounds and psychological tests at 7, 18, and 40 Hz. J. Acoust. Soc. Am. 115, 2388 (2004).
 C. Kasprzak, Influence of infrasound on the alpha rhythm of EEG signal. Acta Phys. Pol. A 121, 61 (2012).
 C. Kasprzak, Influence of binaural beats on EEG signal. Acta Phys. Pol. A 119, 986 (2011).
 C. Kasprzak, The effect of the narrow-band noise in the range 4-8 Hz on the alpha waves in the EEG signal. Acta Phys. Pol. A 123, 980 (2013).
Author: Møller, Henrik; and Pedersen, Christian Sejer
Abstract. The human perception of sound at frequencies below 200 Hz is reviewed. Knowledge about our perception of this frequency range is important, since much of the sound we are exposed to in our everyday environment contains significant energy in this range. Sound at 20-200 Hz is called low-frequency sound, while for sound below 20 Hz the term infrasound is used. The hearing becomes gradually less sensitive for decreasing frequency, but despite the general understanding that infrasound is inaudible, humans can perceive infrasound, if the level is sufficiently high. The ear is the primary organ for sensing infrasound, but at levels somewhat above the hearing threshold it is possible to feel vibrations in various parts of the body. The threshold of hearing is standardized for frequencies down to 20 Hz, but there is a reasonably good agreement between investigations below this frequency. It is not only the sensitivity but also the perceived character of a sound that changes with decreasing frequency. Pure tones become gradually less continuous, the tonal sensation ceases around 20 Hz, and below 10 Hz it is possible to perceive the single cycles of the sound. A sensation of pressure at the eardrums also occurs. The dynamic range of the auditory system decreases with decreasing frequency. This compression can be seen in the equal-loudness-level contours, and it implies that a slight increase in level can change the perceived loudness from barely audible to loud. Combined with the natural spread in thresholds, it may have the effect that a sound, which is inaudible to some people, may be loud to others. Some investigations give evidence of persons with an extraordinary sensitivity in the low and infrasonic frequency range, but further research is needed in order to confirm and explain this phenomenon.
Noise & Health 2004;6:37-57
Author: Huson, Les
This information is provided to assist the relevant authorities when assessing the Navitus Bay Wind Park development.
I have completed a number of infrasound measurements in Australia, the UK and Ireland that were designed to assess the acoustic imissions in the surrounding communities.
I was lucky to have deployed my infrasound recording equipment inside a home 1.6km upwind from the Macarthur wind farm in Victoria, Australia when there was a full unintended shutdown due to a substation failure when the wind farm was operating at almost full capacity. The subsequent start-up was also observed approximately 12 hours later, again at an upwind measurement location. This wind farm had approximately 140 Vestas V112 3MW turbines operating.
The following spectrograms show the dominant tone components in the infrasound region before and after shutdown (figure 1) and prior to and after start-up (figure 2). The vertical frequency scale for figures 1 and 2 is linear from 0Hz to 8Hz.
Figures 3 and 4 show the Macarthur wind farm power generation during the shutdown and start-up respectively.
The average sound pressure level between 0.45 Hz and 6 Hz shows a 3.5 dB reduction when the turbines stopped rotating from a 95% load capacity condition. A sound level increase of 1.5 dB was observed before to after start-up to a load condition of approximately 30% power generation capacity. The tone “lines” in the spectrograms show that structural resonances from the turbines continue irrespective of whether the blades are rotating or parked. The differences between rotors parked or rotating shows as an increase in broadband sound which is responsible for the change in overall sound pressure level from 0.45 Hz to 6 Hz. Structural resonances responsible for the infrasound emissions observed are evident over a wide range of wind speeds.
For normal hemispherical spreading in the audible frequency range it is expected that the attenuation of sound follows a 6dB reduction per doubling of distance from a sound source in the far field. Far field is generally greater than 5 times the largest dimension of the sound source. The near field produces a lower sound reduction with distance and can be zero dB with increasing distance from a sound source if the source is producing a plane wavefront, for example. For irregular shaped sound sources the sound levels may even increase with increasing distance when in the near field
Superimposed upon the geometric attenuation are other factors such as air attenuation and differing amounts of ground absorption. Over water, the “ground” (water/air interface) absorption is negligible.
Infrasound does not follow the hemispherical divergence model of 6 dB reduction in pressure for a doubling of distance (in the far field). There has been a large volume of research work completed in the mid 1980’s by researchers at NASA. Research work on the MOD-1 wind turbine (that was recognised to produce adverse health effects in the community) suggest a geometrical spreading of 3 dB per doubling of distance for infrasonic sound frequencies.
I have completed similar propagation attenuation measurements for two turbines at the Leonards Hill wind farm in Victoria, Australia and have also found an attenuation rate of approximately 3 dB per doubling of distance out to 34 km from the two Repower 2MW wind turbines.
My measurements of infrasound attenuation rates with distance in the near field of the Macarthur wind farm from 1.6km to 5.4km have shown no attenuation with distance. The wind farm dimensions are approximately 5km wide near the residences mentioned.
The London Array
I completed a set of measurements at a residence located 5km inland from Clacton-on-Sea in April 2014. The residence is located in a direct line through Clacton to the London Array that is some 25km away from Clacton.
The residence is also approximately 900m from the nearest turbine in the Earls Hall Wind Farm.
Measurements taken in Clacton allowed identification of the dominant infrasound tones from the London Array to be identified.
Figure 5 shows an example of a single 20-minute infrasound recording taken at the residence near to the Earls Hall Wind Farm. A chart showing the tones associated with the London Array from a measurement in Clacton is also shown for reference.
The key finding is that infrasound tones observed 30km from the London Array and 5km inland are found to be at levels observed from five 2MW turbines located a minimum of 900m away.
This finding has relevance to the proposed Navitus Bay Wind Park. The proposed size of wind turbine for Navitus Bay is significantly larger than the turbines of the London Array and one would expect higher infrasound emissions. Large residential communities border the coastlines of the Isle of Wight and Dorset within 35km of the Navitus Bay Wind Park perimeter. If these populations are exposed to the equivalent infrasound dose one experiences 900m from a 5 turbine wind farm (2MW turbines) then it may be that large scale adverse effects can occur.
I have reviewed the Environmental Statement for the Navitus Bay project and cannot find any assessment of infrasound or low frequency sound. I believe that the development application is deficient in this regard.
Notwithstanding that a large volume of NASA research in the 1980’s already demonstrates potential health effects due to infrasound from wind turbines, in Australia, it has been acknowledged that more research into the health effects of infrasound from wind turbines is needed (Senate Inquiry on wind farms in the community, 2011, and the latest statement from the Australian NHMRC). Such work has yet to be commissioned.
I have experience modelling underwater noise and the effects upon wildlife. I have assessed blast noise impacts on Dugong for the Australian Department of Defence in 2000 and more recently in the prediction of sound exposure level pressures in shallow water from blasting in 2009. I am familiar with the assessment methodologies used in the underwater impact assessment and would simply like to make the following comments.
The impact assessment is heavily biased towards assessing the impacts from piling during construction. The impact assessment clearly shows that avoidance of the areas between the development and coast is likely and that avoidance (as classified in the USA) is “harm”.
A report prepared for COWRIE in 2004 (A review of offshore windfarm related underwater noise sources. Report No. 544 R 0308) states the following:
By far the longest phase of a windfarm’s lifecycle is the operational phase. Two measurements of offshore wind turbine noise are available. These show low frequency sound levels, with a Source Level spectra showing a maximum of 153 dB re 1 μPa @ 1 m at 16 Hz. The measurements are of individual turbines of a relatively low power (less than 1 MW). Despite the low level, low frequency nature of the sound, behavioural reactions have been observed in a study of harbour porpoise (Phocoena phocoena) response to the reproduction of wind turbine noise.
Given that the proposed Navitus Bay development is substantially larger than the single 1MW turbine cited above it would be expected that more relevant recent data could be found to assess the impact of the proposed wind park.
I believe that it would be appropriate to commission a survey in and around the London Array, for example, to get an understanding of the sound pressures involved from a similar scale development.
I have failed to find any reference to offshore wind farms in my copy of Marine Mammals and Noise, Richardson et al, 1995 that is referenced in Volume B Chapter 11. Although reference is made to this book regarding wind farm generated underwater noise, more recent references on the subject should have been provided.
It would be expected that the structural resonances observed via infrasound emission from the London Array (detailed above) would also be observed underwater. The extent of which is worthy of investigation prior to accepting the underwater impact assessment.
W Les Huson, BSc(Hons) MSc CPhys MIOA MAAS MEIANZ
L Huson & Associates Pty Ltd
22 June 2014
Author: Farboud, Amir; Crunkhorn, R.; and Trinidade, A.
Objective: Symptoms, including tinnitus, ear pain and vertigo, have been reported following exposure to wind turbine noise. This review addresses the effects of infrasound and low frequency noise and questions the existence of ‘wind turbine syndrome’.
Design: This review is based on a search for articles published within the last 10 years, conducted using the PubMed database and Google Scholar search engine, which included in their title or abstract the terms ‘wind turbine’, ‘infrasound’ or ‘low frequency noise’.
Results: There is evidence that infrasound has a physiological effect on the ear. Until this effect is fully understood, it is impossible to conclude that wind turbine noise does not cause any of the symptoms described. However, many believe that these symptoms are related largely to the stress caused by unwanted noise exposure.
Conclusion: There is some evidence of symptoms in patients exposed to wind turbine noise. The effects of infrasound require further investigation.
Department of ENT Head and Neck Surgery, Glan Clwyd Hospital, Rhyl, Wales
Department of Neurosurgery, Queen Elizabeth Hospital, Birmingham, England
Department of ENT Head and Neck Surgery, James Paget Hospital, Great Yarmouth, England
Journal of Laryngology & Otology, Volume 127, Issue 03, March 2013, pp 222-226.