Infrasonic's in another thread - can noise canceling headphones block infrasonic's?

Thread Starter

Tonyr1084

Joined Sep 24, 2015
6,954
In a different thread we've discussed some possible causes of physical maladies being due to undetected sounds. So I got to thinking 'Can a "Noise Canceling" headphones block out infrasonic sound waves?'
 

crutschow

Joined Mar 14, 2008
30,419
It's highly doubtful that the circuit, mic, or earphones have any significant response as those frequencies.
 
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Ya’akov

Joined Jan 27, 2019
6,260
It is possible that very specialized noise cancelling headphones could attenuate the sound if not eliminate it. But, as @crutschow points out, the frequency response of ordinary transducers (microphones and speakers) is probably not ging to be sufficient to do the job.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
6,954
Kind of figured standard mic's wouldn't be able to detect infrasonic sound waves. I have heard of speakers that are driven by servo's though. Wondering if a device could be built to detect and cancel them out somewhere like in the bedroom when we sleep.

Just thinking. Nothing serious. Not thinking about anything serious. Not saying my thinking is lacking.
 

Ian0

Joined Aug 7, 2020
5,816
At 20Hz a wavelength is 17.25m, so the pressure will be the same everywhere in the room, so it should be easy enough if you can generate enough pressure to cancel it out. You could use a Pressure transducer as the microphone. You would need a big speaker, mounted in hole in the wall, and possibly quite a lot of power as speakers aren’t so efficient at those frequencies.
Are you sure it’s the infrasonics that is bothering you, or their harmonics?Is this for the embassy in Havana?
 

bassbindevil

Joined Jan 23, 2014
497
I suspect that infrasound is felt more than heard. You might need a mechanically isolated room (supported on springs or air bags and dampers) to eliminate infrasound that's conducted through the ground, as well as Ian0's acoustic cancellation system. Although I suppose a bed with a springy mattress accomplishes that to some degree.
 

Ya’akov

Joined Jan 27, 2019
6,260
Here is a very interesting paper on wind farm infrasound and the possibilities for mitigation. It has cites to sources for potential heath effects, and a discussion of the possibility of using active cancelation methods to reduce it.

I certainly learned some things from it and I am not as sanguine about wind farms located near habitation as I might have been previously, nor am I a willing to accept reports that involve A-weighted SPL measurements, or "I don't hear anything" as proof of harmlessness.

Out of interest, I used an FFT app with the weighting set to flat in my studio-lab and got this unaccountable result:

1659082180581.png
Note the peak are 47Hz, where is that coming from?
This is not a calibrated microphone, and not a scientific instrument but checked against my function generator with a (very) small transducer it seems reasonably accurate in the frequency domain.

The speaker connected to the generator was only about 1" in diameter. With the frequency set to 47KHz I could perceive nothing at all coming from it. Nevertheless when it was on, the 47Hz peak fluctuated with a regular pattern, and off it stopped. I surmise this was beating of the original cause of the 47Hz and the signal from the transducer.

Any ideas of the source? The next peak up in frequency is at 120Hz, so even if I don't have an exact source for that one, 60Hz power provides a reasonable cause in some way. But 47Hz ±1Hz is not something I can account for.
 

Ya’akov

Joined Jan 27, 2019
6,260
By the way, I have quite a few fans running in here from computers to instruments but shutting those off did not change that peak. There is no other continuous emitter than I can figure out.

That peak is consistent in the flat weighting mode, A-weighting peaks bounce between ~208Hz and ~2010Hz. The latter, seems to be the computer fans I don't know where the former is coming from. Though these peaks are nowhere near at divergent from the general curve as the 47Hz peak.

[EDIT: fixed some three orders of magnitude errors in measurement. One OoM is one thing, three is marketing!]
 
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Ian0

Joined Aug 7, 2020
5,816
A-weighting involves first order high-pass filters at 107Hz and 737Hz, so it’s definitely on a 12dB/octave slope down in the infrasonics.
The law, BS4142 for industrial noise here, requires A-weighting measurements, which is perfect for anyone who likes to make low frequency noise! (Night clubs, for example, though repetative low frequency noise is just starting to get included)

However, A-weighting does correspond to the Fletcher-Munson curves at the sort of sound level one would expect for a wind turbine in the medium distance

47Hz is a bit of a puzzle,.

By the way some of your measurements seem to have sneaked in to the medium wave radio band!
 

Ya’akov

Joined Jan 27, 2019
6,260
A-weighting involves first order high-pass filters at 107Hz and 737Hz, so it’s definitely on a 12dB/octave slope down in the infrasonics.
The law, BS4142 for industrial noise here, requires A-weighting measurements, which is perfect for anyone who likes to make low frequency noise! (Night clubs, for example, though repetative low frequency noise is just starting to get included)

However, A-weighting does correspond to the Fletcher-Munson curves at the sort of sound level one would expect for a wind turbine in the medium distance

47Hz is a bit of a puzzle,.

By the way some of your measurements seem to have sneaked in to the medium wave radio band!
Ha. braino† on the kHz, will edit that. The paper does cover the use of the Fletcher-Munson data insofar as they refer to the use of single tones to create the A-weighting. Have you given it a look?

Like a typo but caused by the brain not the fingers.
 

ThePanMan

Joined Mar 13, 2020
468
"I don't hear anything" as proof of harmlessness.
I don't see air, so it can't be there. Right? Generally speaking I don't see pollution either, but I feel its effects.
There is no other continuous emitter than I can figure out.
Wind farm nearby? Say a few thousand kilometers?
Are you saying a certain ex president was on to something? The claim that wind farm noise can cause cancer?
Perish the thought! Got me wondering now too. Although I could hear the noise he made when he described the noise and used a circling hand gesture to indicate it.
 

Ian0

Joined Aug 7, 2020
5,816
Any ideas of the source? The next peak up in frequency is at 120Hz, so even if I don't have an exact source for that one, 60Hz power provides a reasonable cause in some way. But 47Hz ±1Hz is not something I can account for.
You can't beat Google for a straw poll. If you search for "cooling fan 2800rpm" you get quite a lot of hits, so my guess is that you have at least one fan with an electronically commutated synchronous (aka "brushless DC") motor that is spinning at 2800 rpm.
 

shortbus

Joined Sep 30, 2009
9,525
Please stop non-name dropping here. It's not clever, wanted and adds nothing informational to this thread.
You mean to say,"I don't like when you bring up the things he said or did"? I can't mention a name but it is history, sorry to hurt your feelings. But it does seem like he was on to something, or is that on something?
 

nsaspook

Joined Aug 27, 2009
10,097
I thought it was a clever, well crafted post that is applicable to this thread.
A clever, well crafted post would say the real reason for that idiotic 'cancer' statement was about the wallet :

https://ehsrc.public-health.uiowa.e...1/IEC_Wind_Health_Exec_Summary_2019_FINAL.pdf
The McCunney review found evidence that residents who receive compensation for living near wind turbines are less likely to report adverse health e ects than those who live nearby but do not receive economic benefit.
https://consumerist.com/2010/08/01/...000-to-not-complain-about-wind-turbine-noise/
Think fast: if a utility offered you $5,000 not to complain about the noise from their wind turbines, would you accept? What if the noise was so loud that it caused headaches and nausea? It’s a choice Caithness Energy is asking some Oregon residents to make as the utility tries to build one of the largest wind farms in the country.
https://www.google.com/maps/place/C...e30e3e7a2c69b!8m2!3d45.6635021!4d-120.1090438
 

ThePanMan

Joined Mar 13, 2020
468
Infrasound, sometimes referred to as low status sound, describes sound waves with a frequency below the lower limit of human audibility (generally 20 Hz). Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressuremust be sufficiently high. The ear is the primary organ for sensing low sound, but at higher intensities it is possible to feel infrasound vibrations in various parts of the body.
{source} https://en.wikipedia.org/wiki/Infrasound
Goes on to say:
The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath 20 Hz down to 0.1 Hz (and rarely to 0.001 Hz). People use this frequency range for monitoring earthquakes and volcanoes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the mechanics of the heart.

Infrasound is characterized by an ability to get around obstacles with little dissipation. In music, acoustic waveguide methods, such as a large pipe organ or, for reproduction, exotic loudspeaker designs such as transmission line, rotary woofer, or traditional subwoofer designs can produce low-frequency sounds, including near-infrasound. Subwoofers designed to produce infrasound are capable of sound reproduction an octave or more below that of most commercially available subwoofers, and are often about 10 times the size.[citation needed]

Saw "Bill Maher" live one evening. Back when he had his earlier theme music they used what I'll call "Ultra Low Base". More than hearing it I felt it. Like getting hit with a ton of bricks repeatedly. Me, my wife and her mother commented on how intense that was. I have no idea how many woofers they had or at what frequency they were operating at but it was definitely below 20Hz. I don't mean to say "significantly below 20Hz" just that it was VERY deep and penetrating.

I also recall trips to the dentist having a cavity in my jaw drilled and filled. The quiet whine of the turbine driving the drill wasn't all that loud but the sound conducted through my jaw bone was intense. Citations (whales and dolphin) hear with their jaws. They don't have ears but can hear quite well. They also have a "melon" on their forehead that they can change the shape of and broadcast sound waves in a particular direction and then hear the echo location of prey hiding under the sand.

Elephants communicate in the sub-sonic region as well. We can't hear them but they can talk over miles in their elephant language. They say elephants never forget. I wonder what they have to remember.

To say the least this thread has me thinking. I'm associated with a number of veterans who are suffering depression. Largely from their experiences on the battlefield and from other trauma perpetrated upon them by their own service members. I don't want to downplay that, but I'm wondering if some of this PTSD is being exasperated by infrasonic's. Living near a railroad line we often shake and bounce when a freight train travels past. There's also a train that stops and waits for clearance to proceed. The train is approximately 450 yards from my front door, and it idles for quite some time. Never timed it, but I want to say an hour or more.
 

ThePanMan

Joined Mar 13, 2020
468
Something I read from nsaspook post:
"A basic concept from the science of public health requires that a human health risk be a true hazard and that there is exposure to that hazard. This review concludes that there is little scientific evidence that sound from wind turbines represents such a risk to human health."

I guess it could be argued from several different points of view and none of the several will likely agree. Kind of like those "Ghost Hunters" with their electronic equipment. Is it really there? Or is it some other phenomena? Back in the dark ages if someone tripped they might point at an individual and proclaim that person cast a spell on them. That person may be subsequently burned at the stake for being a witch.

Like Chaos-Theory, we don't really know what we think we know and don't really "not" know what we think we don't know.

Being paid for not complaining doesn't necessarily mean there's literally something worth complaining about, but rather an attempt to quell the hype about cancer causing windmills. And we will never know what's truly behind their motives. Tobacco companies downplayed the negative affects of their products all the while working on ways to make them addictive. OK, there we know their motive. I suppose the power company in Oregon is motivated to build their wind farm and prevent people from making complaints that could derail their project. Maybe the sound IS harmful. Maybe not. Whatever the case - we little folks will never know.
 
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