NOISE

This page is dedicated to Noise and possible Noise effects of Wind Turbines. We have provided some background material on the subject for those who wish to learn a little more about the subject.

DART remind readers that this material below, while publicly available, is still protected by copyright.

• Noise Background
• Papers and Reports
• Noise Related Links
• Noise Related Press Articles

Noise Background

Back to the top of the page

The noise frequency range for hearing is about 0 - 20,000Hz (20 KHz). Noise below 200Hz is usually known as "low frequency noise" although this boundary is not fixed. Sounds under 20Hz, which are just about audible (and usually only for very loud sounds) are known as infrasound.

To put this into perspective, the lowest C note on a full range piano is at about 32Hz whilst middle C is at about 261Hz.

The perceived loudness of a sound is measured in a unit called the decibel (dB). The decibel utilises a logarithmic scale rather than a linear one, as the human ear perceives loudness in a similar manner.

What this means to the listener is that a 3dB increase in sound equates to an actual doubling of the sound level. However to the human ear, perceptively, a 10dB sound level increase is considered to be about twice as loud.

So if the noise level increases only 10dB it has doubled. 5dB is half as loud again. So pushing up a noise limit by a "mere" 10dB from say 30dB to 40dB is not so trivial. It just got twice as (2x) as loud.

So in the article below where it shows that noise at night from wind turbines can be 15-18dB louder than during the day, mean that the noise at night is 2 or 3 times louder than the daytime. Quite a big jump...

You read that correctly - 40dB is TWICE AS LOUD as 30dB.

Roughly speaking the sound level from a noise source will drop by about 6dB if you double the distance from the source. A car passing you at about 100 yards distance at about 40mph is about 55dB.

For acoustic noise measurements the "A weighted sound pressure curve" is used. This relates noise levels to the relative responsiveness of the ear to varying frequencies and is expressed as dB(A) [Decibels Acoustic].

Wind Turbine noise falls into 2 categories. Mechanical noise, such as gearbox and generator noise and aerodynamic noise, due to airflow around the blades and also from the air flow between blades and the upright tower, as the blades pass. In addition, noise from adjacent wind turbines can "beat" together, raising the noise level downwind.

In Demark the maximum permitted wind turbine noise level at the nearest dwelling in open countryside is 45dB (A). For residential areas a noise level of only 40dB(A) is permitted. There is currently no equivalent legislation in the UK as far as DART know.

The sound level is only part of the story however, as the aerodynamic noise from wind turbines is often impulsive (i.e. regular thumping or pulsing) at a low frequency and as most of us know from personal experience the bass beat from music played very loud is very disruptive and almost impossible to ignore. It also appears to carry further and penetrate buildings more than higher frequencies, possibly due to the low resonant frequencies of building materials.

It is hardly surprising that ordinances such as the one in Riverside County, California now state that turbine distances from dwellings can be no closer than 2 miles. Riverside County California: "LU 15.9 Restrict the placement of wind turbines within 2 miles of residential development unless the applicant supplies documentation that the machine(s) will not produce low frequency impulsive noise."

Papers and Reports

Back to the top of the page

• The Final Report of the study by Keele University (Prof Peter Stiles) into the "non existent phenomena" of low frequency noise created by windfarms - and which was affecting the Eskdalemuir site is finally available on this link. Be warned - it is 16.5Mb!


• Health effects of wind turbine noise" (2/4/06) by Nina Pierpont, MD, PhD. This is an updated analysis of the "Health effects of wind turbine noise" (2/4/06) by Nina Pierpont, MD, PhD. Dr. Pierpont's credentials can be found on www.ninapierpont.com. Depending on where you are living and her schedule, Dr. Pierpont (who lives in the USA) will testify in court on your behalf if you are suffering from these health effects from wind turbines.


• Wind turbines at night: acoustical practice and sound research by Frits G.P. van den Berg. (151Kb), An interesting paper, showing among other things, that noise tends to be louder at night and also that some noise is perhaps caused by interaction between turbines.
  
• Effects of the wind profile at night on wind turbine sound G.P. van den Berg (624kB), Science Shop for Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands.
  
  • This study is based on a 30MW, 17 turbine wind power station. Residents only 500m or more from the power station have reacted strongly to the noise; even residents up to 1900m distance expressed annoyance.
  • Long term sound emission measurements have been taken (over 400 night hours in 4 months) at distances of 400m and 1500m from the park. In the original sound assessment a fixed relation between wind-speed at reference height (10 m) and hub height (98 m) had been used.
  • Measurements showed that the wind speed at hub height at night is up to 2.6 times greater than expected, causing a higher rotational speed of the wind turbines and up to 15 dB higher sound levels, relative to the same reference wind speed in daytime. Additionally at high rotational speeds the turbines produce a ‘thumping’, impulsive sound, increasing annoyance further.
  • The conclusion is that the prediction of noise emissions at night from (tall) wind turbines is underestimated when measurement data are used (implicitly) assuming a valid wind profile during the day.
  
  
• Danish guidelines on environmental low frequency noise, infrasound and vibration. In Denmark, a set of guidelines for the measurement and assessment of environmental low frequency noise, infrasound and vibration were published in 1997 as "Environmental Review" from the Danish Environmental Protection Agency no. 9/1997" (Pdf- file) (Miljøstyrelsen |2|). These specify recommended measurement methods and recommended limit values for noise and vibration.
  
  This paper is well worth a read.
  
• Acoustic Trauma : Bioeffects of Sound by Alex Davies BFA Honours. (805kB), The work is an investigation into the effects of low frequency sound and infrasound via the design and construction of experimental acoustic emitters. Interesting and with some useful basics at the start of the paper as well.
  
• A Review of Published Research on Low Frequency Noise and its Effects (881kB) Report for Defra by Dr Geoff Leventhall Assisted by Dr Peter Pelmear and Dr Stephen Benton.

Noise Related Links

Back to the top of the page

• Wind Turbine noise problem in Michigan Kelly Alexander lives in Mackinaw City 1300 feet downwind of the two wind turbines. His parents live 1500 feet away. His family hears the noise inside his home. Here you can see a photo of the turbines and Alexander's home, and a map showing the location of St. Anthony's Catholic Church 1¼ miles away, where people sometimes hear the turbines start up. Also here a graph showing the recorded noise levels.
  
  
• Aircraft Noise Effects and Impacts - Aircraft noise has a number of effects on humans including annoyance, sleep disturbance and health effects. This page by the Airfields Environment Trust's Aviation and the Environment Databank has some interesting information on low frequency noise effects.
  
  
• Dr Michael Bryan's Noise Website - An excellent site, informal but full of interesting facts on noise nuisance in general.
  
  
• Some health aspects of wind driven industrial turbines. - An excellent page from the Archive and Collections Society, Ontario, Canada. Particularly the references to minimum distances from housing for wind turbines.
  
  
• Country Guardians's Noise page. - More good information. For example: research at the University of Groningen (Netherlands) shows that existing research on windfarm noise is invalid because measurements have been made at 10 metres. Measurements at 80 metres show up to a 3.5 times increase over 10 metres, with correspondingly higher noise levels.
  
  

Noise Related Press Articles

Back to the top of the page

31st December 2005 Hawkes Bay Today [NZ]: Wind farms may force small school to close. The noise generated by a pair of wind farms proposed for Titiokura Summit could rip the heart out of the Te Pohue community.

8th August 2005 Hawkes Bay Today [NZ]: And the beat goes on . . .and on and on. They call it the train that never arrives. It's a low, rumbling sound that goes on and on ... and on. Sometimes, in a stiff easterly, the rumbling develops into a roar, like a stormy ocean. But worst of all is the beat. An insidious, low-frequency vibration that's more a sensation than a noise. It defeats double-glazing and ear plugs, coming up through the ground, or through the floors of houses, and manifesting itself as a ripple up the spine, a thump on the chest or a throbbing in the ears. Those who feel it say it's particularly bad at night. It wakes them up or stops them getting to sleep.

5th August 2005 The Scotsman: Wind-farm noise rules 'dated' GUIDELINES on noise from wind farms urgently need to be revised, research suggests. One study on the modern, tall turbines now used, conducted at Dunlaw wind farm in the Borders, found that when the 60-metre turbines start to generate electricity, even at low wind speeds, vibrations can be picked up as far away as 10km.

2nd August 2005 Manawatu Standard [NZ]: Meridian pays family to move Meridian Energy has paid an undisclosed sum of money to shift a family from their farm where Te Apiti's wind turbines are located, because noise and vibration made it too difficult to live in their house.

25th July 2005 TVNZ: Flurry of complaints after wind change. Residents in the small Manawatu town of Ashurst say that in an easterly there is an intrusive rumble for days on end. They say the windmills emitted a low frequency noise for three days on end, making their lives a living hell.

6th June 2005 Toronto Star: Israelis unleash Scream at protest New weapon knocks crowds off feet. Sound blast triggers nausea, dizziness. The knees buckle, the brain aches, the stomach turns. And suddenly, nobody feels like protesting anymore.

6th June 2005 Western Mail: Wind farm illness "Having been in the best of health, thankfully, for most of my life, I couldn't understand why I was suddenly feeling very unwell for no apparent reason. Racing pulse, heart palpitations, a strange churning in my head, a feeling of nausea, a terrible unease and a need to escape. Sleep became difficult too."

25th May 2005 Press and Journal: Noise From Windfarm Making Life a Misery A settler in Caithness claimed yesterday his life is being blighted by ghostly noises from his new neighbours, the country's first large scale wind farm.

16th March 2005 This is South Wales: CONCERN AT WIND NOISE ...I Have been undertaking work on the problem of low frequency sound transmission from wind turbines since 1995 and I was part of the team who worked on the DTI Snow Report in 1997. It is clear to me that the downwind sounds from wind turbines have been underestimated and this is supported by the work recently undertaken by Fritz Van Den Berg, of the University of Groningen, in the Netherlands.

21st October 2004 Scoop New Zealand: Windflow Noise Test A Farce The revelation in the Banks Peninsula newspaper The Akaroa Mail (8 October) that Windflow's turbine ran on only 6 days out of the 14 day "continuous running" test period promised to the community further discredits the validity of the test results which were already being seriously questioned by local residents.

14th October 2004: MORE RESEARCH NEEDED INTO TURBINE NOISE Dr Amanda Harry, who has produced ground-breaking research on the effects of noise from turbines on people living near the Bears Down site explains why she is taking her investigation further. (Article reproduced by kind permission of the Western Morning News and This Is Devon).

4th October 2004 Queensland Courier: Wind energy not resident-friendly RURAL residents in two states can't sleep at night because of noise from a Queensland Government-owned corporation's alternative energy projects.

21st September 2004: 'NOISY NEIGHBOUR ON THE HORIZON' New research has backed up claims that the noise from wind turbines could pose risks to health that have largely been ignored. (Article reproduced by kind permission of the Western Morning News and This Is Devon).

12th September 2004: How they "Hide" the Windfarm Noise

16th July 2004: Farmers Weekly: Turbines to land farmers in court? FARMERS HAVE been warned they could face legal action from people claiming damaged health from the low-frequency noise emitted by wind turbines.

14th March: Daily Telegraph: 'In Sickness and in Health by Dr James Le Fanu '

4th Feb. 2004: 'HEALTH EFFECTS MUST BE EXPLORED'. Mounting concerns over the noise effects of wind turbines on the people who live close-by have led to calls for an independent inquiry, as Neil Young reports. (Article reproduced by kind permission of the Western Morning News and This Is Devon)

25th January 2004: Sunday Telegraph - Wind farms 'make people sick who live up to a mile away' Follow this link for the full story.

9th January 2004: 'WIND TURBINES HAVE EATEN INTO MY VERY SOUL' Mark Taplin has lived in the shadow of wind turbines for more than a decade. As part of our on-going debate on the issue, he describes how the experience has affected his life. (Article reproduced by kind permission of the Western Morning News and This Is Devon)

6th January 2004: 'WIND FARMS NOISE FEARS' A medical survey today throws the spotlight on how the noise from wind turbines can have an unbearable effect on people living next them. (Article reproduced by kind permission of the Western Morning News and This Is Devon)

6th January 2004: MORE ATTENTION MUST BE PAID TO THE HARMFUL EFFECTS Plymouth GP Dr Amanda Harry has conducted her own survey on the effect of noise on people living near the Bears Down wind farm in Cornwall. Here, she reveals her findings. (Article reproduced by kind permission of the Western Morning News and This Is Devon)

6th January 2004: SHATTERED DREAM OF QUIET LIFE All they wanted was the good life in Cornwall, and they needed it for the sake of their health - but no sooner had Colin and Kathy Bird fled the city for a modest rural home than their dream was shattered by the noise from wind turbines. (Article reproduced by kind permission of the Western Morning News and This Is Devon)