Windfarm noise – Renowned acoustician denounces double standards in noise regulations

UPDATE: Josh adds a cartoon and writes:

An extraordinary quote from a Scottish Wind Farm Landowner.

But with recent news that wind farms have been paid a secret £13 million compensation to shut down over the last few months it is no wonder all those in the industry are hearing the clink of cash above the roar of the turbines.

If you are wondering what a wind turbine sounds like and what a blight it can be watch this short video.

If, like me, you love birds then you might find this video a bit too sad.But this will cheer you up a bit … and this one.

=============================

FROM EPAW:

Tricks are used to allow wind farms too close to habitations

In an email replying to the European Platform against Windfarms (EPAW), world-leading specialist in low-frequency sound Professor Henrik Moller of Aalborg University denounces the improper acoustic measurements carried out by Danish authorities. As a result, he says, the new regulations for wind farm noise are not in line with industrial noise standards.

According to EPAW, this effectively constitutes discrimination against wind farm neighbors, which now have less protection than other citizens – in Denmark, but also in those countries that may take their cues from the small kingdom.

Henrik Moller and his team of acousticians have been consulted by DEPA, the Danish Environmental Protection Agency. But their recommendations have been ignored: “We had many objections to the proposal, but none of these were accommodated in the final version” (1). Answering a question from EPAW, the Professor explains how the new regulations will not effectively enforce the 20 dB(A) limit of low-frequency noise levels regarding wind farms, but that this limit is indeed being applied to other industries (2). Notes Mark Duchamp, of EPAW: “In reality, this is a case of double standards.”

In his email to EPAW dated Feb. 5, 2012, Professor Moller wrote: “All these errors sum up to probably not far from 10 dB, which means that the limit is suddenly not 20 but rather 30 dB(A). But the rules are claimed to give the same protection as for industrial sources, which is simply not true.”  His letter is reproduced below (2).

“At low frequencies,” continues the Professor, “the perceived intensity, the loudness, increases 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 for higher frequencies is exceeded by the same amount. Few people would probably accept 25 dB(A) in their home at night and hardly anyone would accept 30 dB(A).”

Adds Duchamp: “It would appear that the Danish authorities have been cooking the figures to accommodate the wind industry. Years ago, governments were protecting tobacco companies; today, they absolve wind farms of all sins and help them commit more.”

The North-American Platform against Windpower (NA-PAW) joins EPAW in denouncing these manipulations which threaten wind farm neighbors within and beyond Denmark’s frontiers. EPAW and NA-PAW in turn are joined by the Waubra Foundation, Australia’s best known organization investigating the serious health issues affecting wind farm neighbors.

References:

(1) – Quote from the Aalborg University web page on the new wind turbine noise regulations:

http://www.es.aau.dk/sections/acoustics/press/new-danish-regulations-for-wind-turbine-noise/

(2) – Email of February 5, 2012 from Professor Henrik Moller to EPAW:

Dear Mark Duchamp

The Danish 20 dB(A) limit for low-frequency noise cannot be compared to normal noise limits because

  • it is an indoor limit and not an outdoor limit like usual limits for wind turbine noise
  • the limit applies to the limited frequency range of 10-160 Hz – only frequencies in that range are included – the level of the full frequency range may be higher

Without an acoustical background, it may be difficult to understand how much 20 dB(A) 10-160 Hz noise is, but the limit is the same as for industrial noise in Denmark, and it is in the same order of magnitude as the limits in most other countries that have low-frequency limits (the limit may be defined in completely different ways). Most people will easily hear a noise at that level, and some will find it annoying, in particular if it goes on round the clock.

At low frequencies, the perceived intensity, the loudness, increases 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 for higher frequencies is exceeded by the same amount. Few people would probably accept 25 dB(A) in their home at night and hardly anyone would accept 30 dB(A). Therefore, measurements must be accurate.

In the new Danish statutory order for wind turbines, the noise is not measured but calculated. This need not be a problem, if the calculations are correct. But they are not.

The main problem is the sound insulation used to obtain indoor levels. The statutory order gives values to be used in the calculation, and these values are based on measurements in 26 Danish houses. Unfortunately, wrong measurements.

Sound at low frequencies varies a lot in a room, and according to the Danish rules for industrial noise, 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 indoor levels from the outdoor level. But it was not. The indoor measurement positions were simply chosen randomly and not selected for the high level. Thus the obtained values of sound insulation are too high – by several decibels.

Furthermore, statistical sound insulation values were chosen (from the wrong data) so that 33% of the houses have poorer sound insulation, meaning that the limit may be exceeded in 33% of the cases.

And finally, the calculated values may exceed the limit by a 2 dB uncertainty value. Measured levels from industrial sources are not allowed to exceed the limit.

All these errors sum up to probably not far from 10 dB, which means that the limit is suddenly not 20 but rather 30 dB(A). But the rules are claimed to give the same protection as for industrial sources, which is simply not true.

I hope this helps your understanding.

Sincerely,

Henrik Møller

Henrik Møller

Professor

Section of Acoustics, Department of Electronic Systems

Aalborg University

Fredrik Bajers Vej 7 B5

DK-9220 Aalborg Ø, Denmark

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Gary Hladik

“All animals are equal, but some animals are more equal than others.”

joe

The anti wind people are doing the right things for the wrong reasons. They are not trying to protect people from the devistating problems associated with wind turbines. They are trying to protect the coal, gas and oil industries who do far more damage to peoples health and quality of life. They are selling a devil known by creating doubt about the new devil in town. They learned how to do it from religions. We can’t possibly be raping your children and engaging in daisy chains when nobody is looking. We are pro life and hate homosexuals. Didn’t you read the brochure?

kadaka (KD Knoebel)

When Gaia must be saved,
what’s Green gets a free pass.
What’s always worked before,
must get it in the [assets].
(Pardon me, Mr. Greenpeace rep, but will you be using Fair Trade latex?)

novareason

Living with my window facing a highway, I can tell you how loud some seemingly quiet low frequency noises can be. And the worst part of it is that you can FEEL them as much as you can hear them, so there’s really no way to block out those low frequencies. Explains why so many neighbors to Wind turbines have complained about the noise level, though, if they’ve been cooking the books to make it “Acceptable”.

Just to make this clear; one doesn’t have to be a Professor of Acoustics like Henrik Møller to see that there is one standard for them, and one standard for industry that actually makes things.
I spent just a few hours of my Engineering studies at university on acoustics as such, out of more time on general virbrational analysis. With that inkling of “specialist” knowledge, I immediately suspected that the “measurement” method appears to have been designed to facilitate conformance, not to provide an environment where people can relax and rest.
I suspect that the modes of transmission (as identified in the translation of submission to DEPA by the university) have been deliberately ignored.
Gross theoretical extrapolation from scant measurements are of no practical value to acoustic engineering.. (Does anybody _not_ recognize a pattern here?) And it’s inappropriate theory in some cases which produces “measurements” by which compliance is judged.

John Wright

In my experience, it doesn’t have much to do with decibel level. That can be quite low, but a sound that continuously repeats itself with each pulse identical to the preceding one can be extremely stressful. Electric motors driving blowers or extractors working 24/7 are bad culprits in that respect. I have lived near a river weir; the sound was continuous but the variety of detail within the sound made it soothing. I have also lived near street traffic lights. Once again, the noise level from vehicles was quite high, however it was just about tolerable because it varied. I have never lived near a wind farm, but can well imagine the stress caused by repeated wooshes, even at low Db.
So how do you determine the nuisance level just by counting decibels?

Steve C

The “20 dB(A) limit of low-frequency noise levels regarding wind farms”? dB(A)? The dB(A) scale rolls off steeply at both high and low frequencies, because it is a weighting devised specifically for assessing the noise levels from industrial machinery, which is mostly at midrange frequencies. It weights 160Hz by about -12dB, and anything below 20Hz (where much of the ‘thumping’ from wind farms occurs) by -50dB or more. Accordingly, use of the dB(A) scale for assessing the noise impact from something like a wind farm, which generates its noise primarily at low and very low frequencies, is entirely inappropriate in any circumstances. The standards should either be based on a weighting curve which gives full, or at least near-full, readings at these low frequencies, such as dB(C) (about -12dB at 10Hz) or, better given the frequencies involved, unweighted. Wikipedia article here has the curves.
I would question whether Prof. Moller’s distinction between indoor noise and outdoor noise is particularly relevant at the low frequencies involved. Although it is relatively straightforward to insulate an indoor environment against midband and high frequency noise, insulating it against low frequency noise is practically impossible without resorting to the sort of heavy engineering employed in the construction of anechoic chambers – massive walls, putting the whole ‘environment’ on a soft springy suspension, etc.. Otherwise, LF noise outside –> LF noise inside, with very little attenuation. Been there, measured it with very expensive testgear (not my own, alas).
The LF noise situation from wind farms is bad enough as it is, without the authorities fiddling the figures to pretend that it’s not really a problem at all. Prof. Moller is right to draw attention to this matter.

Jack

Once again, sound science is trashed to give a greenie a go. Too bad the greenies have turned into gremlins, exploiting people’s natural sympathy. Looks like a Yin Yang pendulum has started.

bill

Very good new book on wind turbine noise, experts explaining the subject properly, free from both wind industry dissembling and popular hysteria, see http://www.multi-science.co.uk/wind-turbine.htm

Phillip Bratby

In the UK the wind industry wrote its own noise standards because it knew wind turbines couldn’t meet the standards applied to all other industries. In its desire have hundreds of wind farms, the Government agreed to these wind turbine noise standards. People were not protected from the effect of wind turbine noise, but the wind industry was. That is clearly stated in the Government policy document.

John Marshall

Joe, above, makes some wild claims as to the safety records of oil, gas and coal. There are more people killed in the wind industry than any other power industry. Scrubbed flue gasses are water vapour and CO2 neither of which are a problem.
Wind power is expensive and produces little power. Without the high subsidies it would not be installed. Photo-voltaic cells are expensive and an examination of them by a university in the UK found that payback was 25 years. The cell life was found to be 21 years. So not too good either.
24/7 power can be supplied by nuclear, oil, gas, coal. Tidal will work but not everywhere and is expensive. Hydroelectric is good in some places but can have a limited life due to lake sedimentation rates.

oMan

Berndt Felsche: great comment, especially on the too-common tendency to generalize from too small (and often too constrained) a sample. Daniel Kahneman (“Thinking, Fast and Slow”) describes many cognitive errors –the belief in the infallibility of experts is one–and he says that we are wired to find it hard to reason from general principles and apply baseline data to evaluate our specific case. That requires analysis and research and objective weighting of complex data. We find it much too easy to reason the other way, look at our specific (arbitrary, even contrived) case and assume it will work everywhere. As we are finding out with wind turbines, that assumption may be wrong, and every one of those ten thousand turning blades will remind us of it, by day and especially by night.

sHx

Adds Duchamp: “It would appear that the Danish authorities have been cooking the figures to accommodate the wind industry. Years ago, governments were protecting tobacco companies; today, they absolve wind farms of all sins and help them commit more.”
There is an article in the left-wing Counterpunch newsletter that’s discussing noise levels and community complaints in the US.

A 2010 petition to the EPA by Maine residents —triggered by the Vinalhaven controversy—implored the agency to involve itself in regulating wind turbine noise. It was rejected by EPA and an administrator who referred petitioners back to the same state regulator in Maine who subsequently resigned after the regulatory effort to tame turbine noise was thwarted by political meddling.
Dead still. So quiet that a conversation can carry a mile. Hundreds of feet above the island, wind shear picks up the turbine blades and hurls them around (The sardonic anthem of turbine advocates on Vinalhaven is “Spin, baby, spin”.) casting sound pulses through moisture heavy air. At other times, sound from the turbines skips like a rock on the surface of a cove.
Think of the sounds from a wind turbine as of a thunderstorm. The noise metric, called the dbA scale, captures the peal of thunderbolts. It fails to capture the low rumble of the storm; the vibration and hum of the turbines. Most wind noise controversies are framed around the dbA level because that is how the industry established the metric for sound in the 1990’s. At nighttime in Maine, for instance, the upper limit is set at 45dbA. For ordinary homeowners, though, to prove 45dbA is more complicated than pointing an acoustic measurement instrument and registering its results. Our neighbor group has chased in the middle of the night, in the middle of the freezing cold, pointing microphones and instrumentation at the pitch black sky in an effort to provide statistics and samples that state-hired consultants will accept. You can’t pick up the phone and complain. You have to pay for tests to prove your complaint. On that playing field, ie. what constitutes a verifiable and legitimate complaint, the goal posts keep moving. So far as low frequency noise is concerned, the goal posts that citizens are trying to reach might as well be on the other side of the world.
http://www.counterpunch.org/2012/02/09/big-winds-inconvenient-truth/

The article goes on to make a few demands such as, “2) apply 35 dbA limits to nighttime operations immediately,” which is rather high considering what the Danish scientist says about the maximum tolerable levels of noise (30 dBA).
It is well-worth reading in full.

DirkH

joe says:
February 10, 2012 at 12:46 am
“The anti wind people are doing the right things for the wrong reasons. […] We are pro life and hate homosexuals. Didn’t you read the brochure?”
joe, we know the warmists are wrong but your parody of them is a little over the top.

sHx

I also recommend “spin, baby spin” be henceforth upheld as the official motto of the pro-wind crowd.

DirkH

John Marshall says:
February 10, 2012 at 2:11 am
“Joe, above, makes some wild claims as to the safety records of oil, gas and coal. There are more people killed in the wind industry than any other power industry.”
With one exception: forestry, which is partially a power industry. Deaths and injuries from falling trees, chainsaw accidents etc are so common they don’t even make it out of the local news.

DavidA

In Australia it seems people paid a lot of money to have them on their property don’t experience any health problems. Their neighbours on the other hand soon turn into the walking dead. Funny that.

kadaka (KD Knoebel)

February 2, 2012 4:00 A.M.
Wind Energy, Noise Pollution
Living near wind turbines can be hazardous to your health.

By Robert Bryce
Original with many embedded reference links found here:
http://www.nationalreview.com/articles/289920/wind-energy-noise-pollution-robert-bryce
Copy found here, faster loading without the images or links, on one page:
http://wind-watch.org/news/?p=18597
(PIPA/SOPA disclaimer: site says it’s allowable “fair use” by a nonprofit.)
Good reading, much info.

Christoph Dollis

I hate that this sort of thing happens in the world.
Why can’t people be honest about something so basic?

Rick Bradford

**So how do you determine the nuisance level just by counting decibels?**
I can’t think of a model which could include the enormous nuisance caused by a low-decibel but inquisitive and hungry mosquito…..

Sam Hall

Has anybody considered what effect windmills have on the climate? They are taking energy out of the climate system, there must be some effect.

Pete in Cumbria UK

Here’s a fun game to play with warmista.
It goes like- remind them that rising CO2 causes rising temperatures.So far so good.
Next, point them to this especially with reference to Domestic Electricity prices in Denmark, Germany and Spain. Suggest that rising numbers of windmills and solar panels explain what you see there.
Beware, exploding heads can get messy……

kadaka (KD Knoebel)

From The Telegraph (UK):
Switch-off for noisy wind farms
Wind turbines are being turned off during periods of high wind in case they become too loud.

By Jasper Copping, and Richard Gray
9:00PM GMT 19 Nov 2011
They’ve been throttling back the beasties when the wind is strong to quiet them down, making them even closer to completely worthless.
Which of course naturally leads to this new article:
World’s biggest offshore wind farm opens off Britain as new minister admits high cost
Ed Davey, the new Energy and Climate Change Secretary, has admitted offshore wind turbines are a high cost form of energy as he opened the world’s largest wind farm off the coast of north England.

By Louise Gray, Environment Correspondent
3:36PM GMT 09 Feb 2012
Due to the noise on land provoking too many complaints, wind farm developers are moving turbines offshore, even if it does make them much more costlier to build and operate. (But hey, it’s not like the taxpayers and ratepayers are paying for it, right?)
Animal rights groups sued the US Navy over their underwater sonar disturbing the marine life. Won’t the noise from the offshore wind turbines disturb the sea critters as well? Will the animal rights groups jump up to support their noble cause and sue to stop the offshore wind farms from disrupting the hapless ocean dwellers? Will they rise up to save the innocent intelligent dolphins from this vicious unwarranted onslaught?

Jeff Wiita

joe says:
February 10, 2012 at 12:46 am
Joe. You are sick.

Mariwarcwm

Tolerance of low frequency noise varies from person to person. My sister was nearly killed by the low frequency noise from a windfarm near her house in Wales. Her husband wasn’t affected. They had to sell their house and farm because she was unable to sleep from the noise, which she described more as a vibration than noise. The new owners don’t seem to be affected either. She has exceptionally sensitive hearing, and anyone with similar hearing will suffer badly.

Patrick Davis

“Steve C says:
February 10, 2012 at 1:43 am”
Well said! Anyone who has suffered ear damage, such as myself, and has studied noise, at any frequency, knows this. Politics at work again!

johanna

In Australia, we call it the ‘doof doof’ factor. If you have ever spent a night near where the local hoons drive round and round with their sound systems turned up full bore, you usually can’t hear the music, just ‘doof doof doof’ – the bass notes. I recently spent a night on the ninth floor of a hotel where the noise of the ‘doof doofs’ not only kept me awake, they made things in the room rattle. Earplugs don’t fix it.
Low level bass sounds may not be very loud, but they can certainly be disturbing.

Patrick Davis

“joe says:
February 10, 2012 at 12:46 am
They are trying to protect the coal, gas and oil industries who do far more damage to peoples health and quality of life.”
With coal, gas and oil, generating electricity, even just considering how these fossil fuels provide access to clean water and water treatment plants to millions worlwide alone would prove this part, and the remainder, of you post null and void!

Joules Verne

Think for a moment of all the pain and suffering in the world. Then compare it to a few Danes whining about some low frequency noise a few decibels above some low threshhold disturbing their beauty sleep.
Then think about how obsessed and silly it is to think this is newsworthy.
Can you spell “knee-jerk reaction”, Watts? I knew you could.

Paul Vaughan

“simply not true”
Once again, this is, indeed, where we are.

PJ Brennan

Here’s an article on the same topic in the very lefty (but usually pretty sensible) Counterpunch, on the same topic:
http://www.counterpunch.org/2012/02/09/big-winds-inconvenient-truth/

Curiousgeorge

Since not everyone lives near these wind farms, is there a way to simulate the sound on a personal computer? A downloadable .wav file for example? I think it would help folks understand what the numbers really mean.

Tom

@John Marshall – While there have undoubtedly been deaths in the wind industry, it’s hard to argue that they outnumber those in coal mining!

I immediately suspected that the “measurement” method appears to have been designed to facilitate conformance, not to provide an environment where people can relax and rest.Think for a moment of all the pain and suffering in the world.

@ Curiousgeorge –
“frequency range of 10-160 Hz”
I doubt if many folks have good enough speakers attached to their PCs in order to handle this low a frequency. Many modern speakers may be rated at 20 to 20,000 Hz, but may not give a good reproduction until over 40 or 50 Hz. It may be a rare speaker that gets down to 10 Hz, at least for general home use.

michael hart

I’ll finish the joke for you, shall I ….?
“Something sounds rotten in the Kingdom of Denmark.”
🙂

TG McCoy (Douglas DC)

“How does wind’s mortality rate compare with that from other energy sources? Unfortunately, there is no simple answer. Part of the problem is that statistics on mortality rates for the full fuel cycle of coal, for example, are not readily available. And where available they use different units. Yet, it appears that the current mortality rate of wind energy of 0.15 deaths per TWh is roughly equivalent to that of mining, processing, and burning of coal to generate electricity according to some researchers.”-from:
Wind Energy — The Breath of Life or the Kiss of Death: Contemporary Wind Mortality Rates
by Paul Gipe
Not to mention that coal and natural gas provided warmth and power when the wind doesn’t
blow. Also:
“Split atoms, not birds.”

The Danish plan for higher noise levels being allowed for wind farms can be seen as a future green (well maybe not green- how about red for brick and mortar) job creator.
Think of all the jobs that can/should/will be created to build sound barriers like the ones we have to minimize the noise pollution near freeways. Good paying jobs are there to be had. First you ignore the adverse effects for your preferred industry, then you get sued by some enterprising legal folks. So what would a jury say when the evidence is presented to them. The claimants will have firm data that shows the regulating bodies say it’s ok for X1…..X5 firms in industry Y to pollute the “n” commons to level 1.5* a. Firms in all other industries, not Y, have to have mitigation plans for pollutant a (noise) at levels < firms in industry Y….. Imagine all the jobs that can be created for the legal profession. Any left over money can then be used for the brick and mortar efforts to mitigate "n" to the same level all other industry have to meet……… I think I'd settle out of court……..

hunter

Joe,
Can you make yourself more clear on the windmill issue?
I’m confused: Do you think windmills are a papist pedophile plot, or are the coal and oil interests (you do know that nearly no oil is used to make electric power, don’t you?) are spending money to fight windmills, which at best offers low single digit percentage of power supply? And to be very clear, are you suggesting that those who are opposed are motivated by perverse religious leanings and/or the big energy conspiracy?
TIA,
hunter

anticlimactic

The following is well worth a read on the effects of turbine noise :
http://www.thegwpf.org/best-of-blogs/4894-robert-bryce-wind-turbines-a-noise-pollution.html
Wind turbines are not good at producing useful electricity, they do not save much CO2 [2% to 4%], but they are good at killing wildlife. They are thus ecologically unsound. However the elite 1% can make huge profits from the vast subsidies, which is what really matters. Obviously this aspect is covered in greenwash so the gullible can be made to feel guilty if they object.
If governments specially legislate against their people to protect the profits of the few I can see a time when people start trying to find out how easy or difficult it is to stop a turbine working.

johanna

Since wind power can never replace other sources (which always need to be there as a backup), even one negative effect is gratuitous and avoidable.
Every bird, bat and human that dies or is injured by a windmill has been sacrificed for nothing.

Low freqs, especially below 30 cps, can be stressful in ways that aren’t shown on the dB meter. The lower you go, the more it affects your entire body instead of your ears. Such freqs also tend to induce sympathetic vibrations in walls and floors.
Because your auditory system tends to ignore these freqs, you aren’t conscious of it, so the stress can build up.
Example: the school near my house has a heating fan that sometimes goes wrong, producing a low rumble. I may notice that I’m twitchy and wiggly, but I don’t pin down the cause until the heating fan [presumably] reaches its limit of eccentricity and shuts off due to overload. The sudden silence finally catches my attention: “What was that?!” … and the twitching and wiggling stops with a vast sense of relief.

I think bird mills are scary, noisy, inefficient and expensive. They are now used by the National Weather Service in the US as icons for windy conditions at forecast.weather.gov
The wind farms get paid by the taxpayers to both produce and not produce electricity.
What’s there to like them?
Thanks, Anthony!

@Curiousgeorge says:
February 10, 2012 at 5:16 am
Since not everyone lives near these wind farms, is there a way to simulate the sound on a personal computer? A downloadable .wav file for example? I think it would help folks understand what the numbers really mean.
I am a member of a grassroots group trying to stop the senseless industrialization of the eastern shore of Lake Superior by these useless wind ‘power’ (sic!) developments. At a recent open house we played IWT sounds, recorded by an audio engineer, through a decent stereo system with a 12″ subwoofer and good tower speakers. The volume was set to measure 40dBA across a 20′ room, using a cheap decibel meter.
Our group had rented the room next to the developer’s and set up our information booths, videos etc… We turned the speakers so that they faced the closed doors and wall between our room and the developers and put the IWT playback on repeat.
The sound of the IWT could be heard through the sound tracks of our videos and the conversations of an average of 25 people in our room and the 50 or more in the developer’s. It was a constant intrusive background that never allowed the subconscious to tune it out. Some people were more annoyed by it than others – especially the developers who complained bitterly that what we were doing was unfair, prejudicial and unscientific 🙂 Some people even claimed that the noise made them slightly nauseated.
The point of this story, other than to share our enjoyment at the poetic justice, was to point out that even with a very good sound system and speakers you won’t get the full effect of the IWT noise. First of all it is very difficult to accurately record the low frequency & infra-sound given off by IWT. Secondly most sound systems are designed to optomize the response in the 20Hz to 20,000 Hz range, that of our hearing and will thus not properly reproduce the lower frequencies produced by IWT. Furthermore it would require very large subwoofers and powerful amplifiers to generate the equivalent sound pressure an IWT does.
So a PC with good speakers won’t do the job – but it will probably do it well enough to annoy windbaggers, LOL
@Joules Verne
Think of all the pain & suffering in the world and then compare it to a few people whinning about their human rights being being violated through interrogation, sleep deprivation, water boarding or torture.
Then think how silly and obsessed it is to think it newsworthy!
Can you spell “knee-jerk” reaction, Joules? I’m sure you can…
Can you spell troll, Joules?

One of the aspects of low-frequency sounds is that they are readily structure-borne. In some cases, sound levels within structures can be greater than outside. Gross structural resonant frequencies tend to be between 3 and 10 Hz and will pass more easily through the structure than free air.
Speaking of frequencies, with the speed of sound at 330 m/s, low frequencies can establish resonance (standing waves) within room by reflections between walls. IIRC from 30 years ago, this can result in a doubling of acoustic pressure; a 3 dB increase. Furniture, etc can ameliorate the effect but why redecorate because of a wind generator outside?
As others have observed, acoustic annoyance is down to much more than a weighted sound pressure level. 20µPa is the reference pressure for the decibels and “A” is an arbitrary weighting that approximates the “average” hearing sensitivity of the human ear to moderate acoustic pressure according to frequency. The weighting only corresponds closely to the actual sound pressure around 1kHz. Hearing is a psycho-acoustic response that varies with the pressure level. The A weighting is really only appropriate for moderate noise levels.
Actual pressure levels are much higher at low frequencies than the A weighting indicates. According to the yellowing B&K (somehow appropriate!) acoustic noise measurement guide that I’ve just pulled off the shelf; at 20Hz and 20dBA, the sound pressure level is 80 dB (re 20µPa) so the pressure to move stuff is substantially more intense. Hence the tendency to be able to “feel” low-frequency sounds which are below the hearing threshold.
B&K cautions “It should be recognized that scales developed to rate one particular type of noise may give wildly inaccurate predictions when used to rate another, especially if their spectral and temporal characteristics differ significantly”.

beng

The warmarxists hate water-torture of terrorists, but sound-torture of law-abiding citizens is OK.

@Curiousgeorge says:
February 10, 2012 at 5:16 am
Since not everyone lives near these wind farms, is there a way to simulate the sound on a personal computer? A downloadable .wav file for example? I think it would help folks understand what the numbers really mean.
I am a member of a grassroots group trying to stop the senseless industrialization of the eastern shore of Lake Superior by these useless wind ‘power’ (sic!) developments.  At a recent open house we played IWT sounds, recorded by an audio engineer, through a decent stereo system with a 12″ subwoofer and good tower speakers.  The volume was set to measure 40dBA across a 20′ room, using a cheap decibel meter.
Our group had rented the room next to the developer’s and set up our information booths, videos etc…  We turned the speakers so that they faced the closed doors and wall between our room and the developers and put the IWT playback on repeat.
The sound of the IWT could be heard through the sound tracks of our videos and the conversations of an average of 25 people in our room and the 50 or more in the developer’s.  It was a constant intrusive background that never allowed the subconscious to tune it out.  Some people were more annoyed by it than others – especially the developers who complained bitterly that what we were doing was unfair, prejudicial and unscientific 🙂  Some people even claimed that the noise made them slightly nauseated.
The point of this story, other than to share our enjoyment at the poetic justice, was to point out that even with a very good sound system and speakers you won’t get the full effect of the IWT noise.  First of all it is very difficult to accurately record the low frequency & infra-sound given off by IWT.  Secondly most sound systems are designed to optomize the response in the 20Hz to 20,000 Hz range, that of our hearing and will thus not properly reproduce the lower frequencies produced by IWT.  Furthermore it would require very large subwoofers and powerful amplifiers to generate the equivalent sound pressure an IWT does.
So a PC with good speakers won’t do the job – but a home stereo will appaently do it well enough to annoy windbaggers, LOL
@Joules Verne says:
February 10, 2012 at 4:36 am
Think for a moment of all the pain and suffering in the world. Then compare it to a few people  whining about some infringement of their human rights through sleep deprivation, stress positions or maybe even a little waterboarding.
Then think about how obsessed and silly it is to think this is newsworthy.
Can you spell “knee-jerk reaction”, Joules? I knew you could.
Can you spell troll, Joules?

oldgamer56

While I have some hearing loss from my time in the military, I am very sensitive to low frequency noise. I was running a table saw in an industrial setting and was bothered by a continuous booming that was rattling my head, After turning everything off in the shop, I was lead by the noise outside, where a woman with small children was sitting in a running car with the bass turned up. I politely asked her to turn the base down.
Wonder if I can claim victim status under the American with Disabilities Act. Low frequency sensitivity. Maybe I can sue boom box makers!

RobW

It never fails to amaze me how the mass development of ‘Bird-o-matics’ is acceptable to the green lobby. Yet a few dozen birds dying in tailing ponds is reason to mount a world-wide protest. Pure and simple hypocrisy!