Meassuring infrasonics created by wind power plants, anyone?

[DerEber]

Dear friends,

in my hometown and around they try to build more and more wind power plants. Now in the local newspaper there is a great amount of people bashing against each other and one of the biggest point seems to be the infrasonic sound the plants might produce and the possible problems for health.
The whole discussion is covered with a great lack of understanding basic acoustic prinziples. Some even can't spell infrasonics right.
Well I am really digging green energy, but I heard of people who seem not to be able to sleep properly and the faces of the citizens' initiative groups really make me worry.
Is anyone here having experiences in this field?

I think infrasonics can affect people. 30hz at full power can be scary. Also anyone remembers the Alpha-Wave meditation CD's ? ;D
I think it was the 7 Herz between left and right headphone with was supposed to set you in a buddha like state.... well.... didn't work for me.
How low can you measure with normal measurement mics? Any recommendations?
I am also thinking that if infrasonic is really entering the house it should be measurable as a surface vibration on windows and walls. Any chance for me to build something with a piezzo?

After all for now I only can imagine serious problems if the infrasonics are hitting the resonance of the whole building. This will probably less an issue in regions were you build earthquake save. Here in Germany we don't. If the building is resonating I possibly could sens it my hand
And I suppose that frequencies below say 8 Hz won't enter buildings at all.

Any comments on this are heartly welcome.
best,
Stephan

 

[Gus]

some links
https://wattsupwiththat.com/2014/08/26/bearings-the-achilles-heel-of-wind-turbines/
https://wattsupwiththat.com/2012/03/06/wind-turbine-syndrome-affects-more-people-than-previously-thought/
https://wattsupwiththat.com/2016/01/23/saturday-silliness-wind-turbine-photo-of-the-year/de-icing-wind-turbine/
there are more

 

[JohnRoberts]

Dear friends,

in my hometown and around they try to build more and more wind power plants. Now in the local newspaper there is a great amount of people bashing against each other and one of the biggest point seems to be the subsonic sound the plants might produce and the possible problems for health.
The whole discussion is covered with a great lack of understanding basic acoustic prinziples. Some even can't spell subsonics right.

No doubt, the proper term is infrasonic (below audible frequency).

Sub-sonic refers to speeds slower than the speed of sound.

Well I am really digging green energy, but I heard of people who seem not to be able to sleep properly and the faces of the citizens' initiative groups really make me worry.
Is anyone here having experiences in this field?

not me

I think subsonics can affect people. 30hz at full power can be scary. Also anyone remembers the Alpha-Wave meditation CD's ? ;D
I think it was the 7 Herz between left and right headphone with was supposed to set you in a buddha like state.... well.... didn't work for me.
How low can you measure with normal measurement mics? Any recommendations?
I am also thinking that if subsonic is really entering the house it should be measurable as a surface vibration on windows and walls. Any chance for me to build something with a piezzo?

After all for now I only can imagine serious problems if the subsonics are hitting the resonance of the whole building. This will probably less an issue in regions were you build earthquake save. Here in Germany we don't. If the building is resonating I possibly could sens it my hand
And I suppose that frequencies below say 8 Hz won't enter buildings at all.

Any comments on this are heartly welcome.
best,
Stephan

Wind turbines are a major problem for birds/bats, humans not so much, while I've heard complains about close to residential areas.  I guess europe is one big residential area.  ;D

JR

 

[thermionic]

OTOH, I can think of a couple of options to investigate: 

i) specialist accelerometers, coupled to low-noise preamps. Bear in mind that, for your application, I suspect you'll need pretty high-end hardware. A quick Google search found this as an example:  http://www.pcb.com/testmeasurement/accelerometers/hisensitivity

ii) Laser vibrometers. Example:  http://www.polytec.com/uk/products/vibration-sensors/

If you want it to hold up in court you'll need to hire a specialist in vibration measurement. I can tell you for a fact that this won't be a cheap experience.

Good luck!

 

[gyraf]

..remember that wind itself is the main source of infrasonic environmental noise - and it comes at at extremely high sound pressures..

I think the focus on this area comes from poor understanding of stress-induced low-frequency tinnitus (but that's only my personal theory).

Jakob E.

 

[Script]

Meditation CDs are at 7 Hz? Damn, I tried to emulate but picked wrong frequency. Explains why I'm always so n rvous.

Anyway, please record and send. Will try to market it here. Some people here could very well do with a bit of enlightenment.

 

[DerEber]

No doubt, the proper term is infrasonic (below audible frequency).

Sub-sonic refers to speeds slower than the speed of sound.

Thanks  ;D

 

[ricardo]

In Oz, the Fossil Fuel Climate Change Denier morons have persuaded the govt. that yet another "scientific" investigation into this is warranted for $$$$ of Taxpayer's money ...  as ALL existing and previous studies have shown NO such effect.

I'm privy to some inside info from Ar*p who conducted the most recent study.  They found normal wind noise at those frequencies (nothing to do with windmills) completely swamped the windmill noise ... unless you were literally directly at the base of the tower.  Even then, the most annoying noises weren't infrasonic.
___________________

If you want to investigate this yourself, any single diaphragm omni condensor capsule can be modified to respond to DC (at least 0.1Hz) ie act as a barometer.

There will be a tiny pressure equalising hole which determines the LF cutoff.  This is obvious in B&K measurement mikes and a drop of glue to seal the hole does the trick.

Then the only rolloffs will be electrical.  The obvious one on a Schoeps  type circuit is the caps between S & D of the FET to the emitter followers.

Less obvious is the capsule capacitance and the 1G or more Gate resistor.  Today, 5G resistors are cheap and you can use several in series.

Larger capsules have bigger capacitance so go lower.

DO NOT USE double diaphragm capsules or transformers.

Don't forget the LF roll-offs in your preamp too.

 

[DerEber]

some links
https://wattsupwiththat.com/2014/08/26/bearings-the-achilles-heel-of-wind-turbines/
https://wattsupwiththat.com/2012/03/06/wind-turbine-syndrome-affects-more-people-than-previously-thought/
https://wattsupwiththat.com/2016/01/23/saturday-silliness-wind-turbine-photo-of-the-year/de-icing-wind-turbine/
there are more

Thanks Gus, it seems like there are more good articles to be found in English than in German. My searches lead most of the time to Anti-Windmill sites that have more the look of a sect and no usefull information.

In the second article they even used a suffix to the db 

"This prompted their issuing regulations that limit low-frequency noise levels inside homes to 20 dB(A). Unfortunately, as denounced by Professor Henrik Moller, they manipulated the calculation parameters so as to allow LFN inside homes to actually reach 30 dB(A) in 30% of cases. “Hardly anyone would accept 30 dB(A) in their homes at night”, wrote the Professor last month"

Anyhow this is useless. 20db (A) will be a different beast at 25Hz or at 10 Hz.

 

[DerEber]

If you want it to hold up in court you'll need to hire a specialist in vibration measurement. I can tell you for a fact that this won't be a cheap experience.

Good luck!

Well I try to avoid courts until I die.  ;D

But cool would be if I were able to make a SPL measurements down to whatever is necessary and not spending a fortune.
I mean, I could spend a 4 digit number with a "1" on the first place, but would also love to to spend half of that and get things going.
I need to inform myself better and see whats option I have. My head is spinning now.
Building my own mic is out of my available time right now.
Building a Preamp would be no problem for me and than a LPF and I can come with my Oszi. That would be quick and dirty.
I have no experiences with measurement mics. Cheapo Behringer seems to suck at LF.
The Earthwork goes down to 5 Hz.
http://www.thomann.de/de/earthworks_audio_m30.htm?ref=search_rslt_messmikrofon_213363_17
Another option I an thinking of is to ask MBHO as in the Studio I belong to we are thinking about buying a pair of Omnis for long now.
http://mbho.de/pdf/ka100lk_ka100dk_ka300nb.pdf
Maybe he has an idea for me and this could be paid by the studio.

In the end I won't be able to tell if people realy get sick of this. I think a lot of this is imagination and many of us can tell a tail about what one is thinking to hear all the time..... even if it is not there.
But I sure can tell what LF SPL would scare me and I'd be happy to go out there measuring and tell them not to worry.
Or maybe there are cases where the whole building is resonating at LF and I would also be happy to examine that.


Btw. this is the greatest forum on earth. I can come up with just anything I imagine, and get professional answers!!!!!
(Any Idea where my strange cough comes from)

 

[Script]

(Any Idea where my strange cough comes from)

Most recent research points to ultrasonic sound emitted by solar panels 

 

[audiomixer]

There are a few topics here to think about in no specific order:

measuring infrasound: we use a B&K meter here at work with extended frequency response below 20Hz, and most notably it has a frequency response chart for the entire system.... The DIY route will not provide a known frequency response for the infra sound - neither the microphone nor the I/O. the I/O will probably have a highpass anyway. so you can't expect to measure SPL re 20uPA anyway. but you might be able to measure relative spectra. will it help?

wind: you are obviously going to measure during a windy period. whatever reading you get will be highly compromised by that. I can only think of an A / B long term correlation between measurements at the same spot with the 'same' wind conditions with or without the turbine actually running. but then the added noise of the mast and stationary blades would have to be taken into account too. seems like a chicken / egg problem. can you get the power company to stop the turbine for a (windy) day?

vibration measurement and harmonic content: this seems a plausible way to get data. if your rotor is spinning, it will emit to a regular frequency, so try to correlate with rotation speed (and blade count, of course). vibration pattern on the mast measured with an accelerometer should match too, I presume. might line up with with microphone data....

infra sound in general: there are tremendous amounts of  sub infra LF garbage around us anyway. very difficult to attribute it to a source. I am not saying this is innocuous, but its here anyway.

scientific research: there is a proposed measurement setup floating around in the acoustician ans DIN / ISO / EU Norm world that is being discussed as well as scientific data. I would not think its biased by default, on the contrary, it seems basically valid. I would try to sum up the research first, many smart people have done some of the stuff you are considering I guess...

acoustical camera: that would be interesting. you might get much more information on the source location that way, but don't forget the size of the sensor required to 'see' low frequency source location.... probably not practicable for the DIY. maybe there is some research on that too, I am thinking of Aachen and Delft university, they are stong in that field....

there seem to be much 'noledge' floating around, but most of it emanating from a already fixed standpoint. I would try not to get caught on any side of that discussion..... but then there is no big wind turbine farm around where I live.....

- Michael

 

[thermionic]

I'm not sure who you'd ask in Germany, but here in the UK, you could approach the ISVR and ask if they had any students interested in the field:  http://www.southampton.ac.uk/engineering/research/centres/isvr.page

Is there a Max Planck Institute department that would  handle this?

 

[JohnRoberts]

At the risk of stating the obvious if this is so hard to measure there may not be much there there.

Perhaps research seismology (earthquake detection) technology.

JR

 

[DerEber]

Ok finaly I found a good reading:

http://www.buerger-fuer-eggebek.de/downloads/wkalaerminfraschallanwka.pdf

People who are measuring Infrasonics already for detecting Atomic detonation etc.
Its in German language only.......

They use this microbarometers for measurement.
http://www-dase.cea.fr/public/dossiers_thematiques/microbarometres/description_en.html

best,
Stephan

 

[Andy Peters]

At the risk of stating the obvious if this is so hard to measure there may not be much there there.

This is what I was thinking.

Sounds like some weird offshoot of homeopathy ...

 

[thermionic]

At the risk of stating the obvious if this is so hard to measure there may not be much there there.

This is what I was thinking.

Sounds like some weird offshoot of homeopathy ...

Homeopathy itself isn't weird enough?

 

[DerEber]

This one is nice on infrasonic: 

http://www.rotarywoofer.com/Africa.html

 

[audiomixer]

Ok finaly I found a good reading:

http://www.buerger-fuer-eggebek.de/downloads/wkalaerminfraschallanwka.pdf

this is a very interesting read indeed. to bad that the human aspect is not looked at in detail. the technology used to measure infra sound is very advanced. I like the seismic array to gain directionality...

- Michael

 

[Gus]

I think something like this affixed on the top of a rod pushed in the ground might "hear" the low frequencies
http://www.taydaelectronics.com/breakout-boards/adxl335-3-axis-accelerometer.html
Maybe with the The X,Y and Z readings you could do some math to tell direction