Mystery Low Piched Humming

Transformers are a common source of low hum (furnace stuff is notorious). Some things build up charge and continue to give off a hum even when the power is off, for quite a while (check any power supply for example). So it's not impossible the source of hum is still in your house, especially if closing the windows doesn't help.

On the other hand, streetlights (and their transformers) are also notorious.

For the cheapest ever Acme Low Hum Detectorisationer, you can pick this stuff up and locate the source with the $4.95 "Magnetic Pickup" shown here. The little "Audio Amplifier" below it at $14.95 works perfectly with this and other probes; you'll clearly hear the hum (your wife can even tell you if that's the one or not); it has a headphone out you can use to analyze the signal output or make recordings if you need em to get action on the hum source removal people (whoever they are!).

Good luck.

Thanks Artsmith, interesting link.

Also this raises a question my mind, does wind direction affect it? The net is tightening.

The equipment you link to seems to detect emf, and render it audible. I think my neighbour must have one then, if you see what i mean. If the cause of the noise is emf, it is being translated into sonic vibrations already, and that's what we can hear.... I think I need something that detects the sonic and translates it into visual.... turn left, higher reading, turn right, lower reading type of thing...

Thanks for thinking about it for me..

JIm

It's Del and Kris mucking about:

That's funny!!!

I would have initially suspected that you'd recently installed fluorescent lights somewhere in your house, but you said you still heard the hum even after you shut off power to the house. They can generate a very annoying hum that seems to come from everywhere.

Are there any outdoor lights near your house that require an electronic ballast to operate (street lights, neon signs,...) The ballast can generate a humming noise, and the noise can echo around so it's hard to pinpoint.

If you can't eliminate the hum, you might buy one of those white noise generators that provides a peaceful background that can mask the humming noise.

Nope, we don't like fluorescents, I will check the street lights, we have had the radio on quietly during the night, which helps.

The noise is almost subsonic, to me at least, and as such I think it can travel, like you say, to mask where it is coming from, like putting your woofer (sorry Del) behind the sofa.

The wife seems to be becoming sensitive to it, it gets more irritating as the nights pass, which is great fun for me. She says she can feel it shaking the bed slightly

I wonder what speed an extractor fan runs at, and if that or a multiple of that corresponds to a very low hum frequency... harmonic resonance...

Jim

Is it possible that you have a water leak? A water line in the wall can make a humming vibrational sound that may be transmitted anywhere. Maybe your outside water spigot is open and running? A runny toilet?

Yes - A running toilet.

Just recently I had a low frequency that would wake me at night. No one else could hear it. I noticed that if I flushed the toilet that it stopped. At first I thought that the flush sound was overpowering the hum. But when I turned off the angle stop (water supply) to the toilet the sound stopped. I replaced the fill valve and the problem went away.

It is also possible that drain pipes are carrying the sound from the festival to your home. We had this problem at Disneyland years ago. An attraction was heard by a neighbor 3 miles away when the sound could not be heard just standing outside the building of the attraction. The fix required building an acoustical trap for the sewer to this building to attenuate the offending frequency.

Although my primary discipline is electrical in nature, I was recently boning up on the operation of our shiney new Wobbe index meter and had to dig deep to remember what I had learned years ago about the Strouhal effect. This makes me wonder if you might not have a leaky valve somewhere that you can only hear when it's very quiet. I suggest you turn off all the valves in your house that you know of and record the meter reading. Check it again in half an hour to see if it's changed. At lest you'll rule it out as the problem. Worst case; it does change and you don't know where the hell it is! Good luck!

Jim, you don't say what part of the planet you are from, but depending on surrounding geology, some very low frequency vibrations can be coupled through the earth and then into the structure of your house. Things like mining equipment or oilfield pumping operations can do that. You could start by trying to triangulate using a relatively large (because the signal is such a long wavelength) parabolic microphone connected to an SPL meter with a low pass filter and a headphone output so you can identify the sound you are looking for. start with your house and rotate the parabolic reflector until you find the signal of interest and note the bearing line that it is on and the intensity from the meter. plot that bearing line on a map. then pack it up and travel a few blocks at an angle (more or less perpendicular is preferred) to the bearing line noted. Repeat the process to get a new bearing line. Plot it too on a map. Do this a couple-three more times, moving closer to the intersection point of the bearing lines each time. the intensity should steadily increase as you get closer to the source. you should be able to pin down the source location to probably within a hundred feet or less and then have a decent chance and figuring out what the source is.

I will try the leaking water theory tonight.

I am from Derbyshire uk, home of Radon there is mining but not recently started., whereas our noise has just started.

'you should be able to pin down the source location to probably within a hundred feet or less and then have a decent chance and figuring out what the source is.'

There are multiple suspects within a couple of hundred feet, vents and extractors from pubs and takeaways, restaurants, etc. Walking through the courtyards and alleys, it is always the closest that is loudest. Something is making a low frequency hum, and your 'low pass filter' and a large parabolic reflector might just find it for me.

Jim

Now that you mentioned mining, could there be some machinery, like pumps or fans running in connection with the mining operation? You said "it was not started", but could there be some preliminary preparation work going on underground? Since the noise has started to coincide with mining, there appears to be a strong link. The mining operation may also have some unshielded electrical equipment.

Another thought: Could it be your refrigerator? Mine puts out a low hum all the time, but I don't hear it unless I put my ear up against it.

Hi Ronseto. I should have put 'just started', in that there is quarrying a few miles away, but it has been going on for years. Likewise with the fridge- it is relatively new but the noise started a while after the fridge arrived. Also, we still get it with the power off, although another poster said freon can continue to circulate, so tonight the fridge gets unplugged.

I have put out an APB on some mics and recording gear.

Jim

Perhaps the quarry has installed a new or different type of crusher?

You mentioned harmonics (multiples of existing frequencies) in an earlier post. I read, as a teenager (40 years ago, mind you!) of some work done in a factory town in America (don't remember what state, but I think it might have been Pennsylvania) where new exhaust fans had been installed, and sub-harmonics had been identified as the cause of virtually instant insanity on the part of one worker, who became homicidally enraged during his work shift. Happily, he didn't kill anyone, as his coworkers recognized very quickly, though they didn't know the cause, that his behavior was totally out of character. But what brings it to mind was that HIS workstation, alone, was the physcal focus of two frequencies created by the new extractor fan bearings, which resulted in either a 13 or a 17 Hz harmonic ( can't remember which, but one causes great and unpredictable anger, and the other depression, in a large percentage of people exposed to it, to some varying extent).

The reason I give all this background, indeed, the reason I bring it up at all, is that you may have to find two sources of sounds that are not even near your perceived frequency (harmonics appear as sums, and differences, and even a couple of fairly high ultrasonic signals of strong presence, if the difference is near your hum frequency, can cause a strong harmonic). The process of finding them, then, would include first, as you suggested, the step of localizing the sound as to source, by basically "triangulation", but if you don't find a fundamental source there at the frequency you need, you'd then need to find two sources relatively near, and at relatively strong magnitude, of signals that are THE HARMONIC FREQUENCY apart from each other. That in itself might not be as hard as it sounds, since the hemispheric propagation laws for sound follow the inverse square law for distance vs amplitude, and the harmonic itself is only roughly one-half the average power of the two fundamental frequencies. So, find the point where the harmonic is strongest, then identify the spectrum of frequencies that hit that point, and the two of those that satisfy BOTH of these criteria, a) they are the harmonic apart in frequency, and b)at that focus point, they are of equal, or very nearly equal intensity (this last part won't be precise, due to such things as transmissivity of nearby physical objects, and, if the signals are at or near audio ranges, say, < around 25 Khz, air currents can change their apparent strength). Then, track down the physical source of both signals, and figure out which one you are most likely to get the council to act on, and show them what you've done.

Unfortunately, unless the council either includes an engineer, or someone who, like me, finds physical mysteries fascinating, or someone of above average intelligence (I don't know about where you are, but in the US, intelligent people seldom make it onto governing bodies. Witness our current Congress, Senate, White House, etc., if you need proof), so getting them to understand, let alone act on, applied science, is really tough. Usually its quicker to show them why it would be politically useful TO THEM, to get them to do so.

Sorry for the length of this, but its hard to cover the details of the audio physics involved, even for intelligent people like you, without a lot of words. But I've had to do exactly this in some of the Sound Distribution and Reinforcement design work I've done. Its a pain, and hard, and takes a long time and a lot of work, but it DOES work, and it sounds like in your case, it might save you from your wife getting homicidal (You think I'm crazy NOW? Wait'll you see what happens if you ignore that noise and I have to live without sleep for another week! I'll show you HOMICIDAL!!!)

We don't want to lose you, so good luck.

I also mentioned there were few aircons around. Suddenly I have stared noticing them. Not in a direct line of sight from my house, but there is a cluster of 5 not far away, 300yds. The architecture round here isn't all straight roads, there are lots of courtyards and curved buildings and walls on an angle.

Standing with my back to one of these large flat angled walls i can see at 2 o'clock my house, and at 10 o'clock, the cluster of aircons, one a noisy one.

I take your points about getting action, and the problems dealing with people who think they know more than I do but talk rubbish. And it can be people you would imagine would know better, like you say.

On a side note, in counselling there is a technique called reflection. You simply say to the person what they have just said to you. After reflecting a few statements that are obviously rubbish, 'so you're saying to me that....' you will start to see the disbelief appear in their eyes at their own remarks.

The house may be at the focus of two frequencies. If I can't find one cause, I will be back on to you with what I have found, to pick the bones out of it for me. It may also be at the physical focus of sound reflected around corners.

This isn't getting easier, but I am getting closer. Thanks for the ideas

Might be someones air conditioner/s. in which case, if it is, you may have to wait till fall. Once the weather cools, your hum will go away.

Yes, there aren't many aircons around here yet, it's not that warm/cold, but there are some starting to appear.

The mystery is it continues thro the night, whereas the extractor fans do not.,Is aircon an allnight thing? Also, it started as the weather went cooler. We actually had a few weeks of sun, a rarity these past years, and it started as it went colder, and wet (in time for the festival I mentioned)

Jim

could have been a de-humidifier, or an air filtration system,

Can you determine if the hum is 60 hz. If so, it could be a pole line transformer going bad.

The archway is acting like a parabolic reflector, it is merely concentrating ambient sound, it isn't the source. not unlike the whispering gallery in many churches.

http://en.wikipedia.org/wiki/Whispering_gallery

As to the geologic conduction path I mentioned, Seismic energy can act much like a SOFAR channel in the deep ocean.

http://en.wikipedia.org/wiki/Sofar_channel

Here is another possibility...

http://www.nexteraenergyresources.com/pdf/Epsilon_study.pdf

lots of insects will hum and sound like electrical noise. I had that noise around my house for a summer and again this summer. It is very hot and humid and not cool as you report. Ladybugs, cicada beetles, etc. If it sounds like "yellow submarine" it is definitely the Beatles.

round again eh. you are supposed to search the site before posting, as low frequency issues have been discussed here before. (sample)

Chris

Hi Chris

Sorry.I did forget to search the site. The CR4 email came in and I thought 'Those guys will Know' .I was tired. I've been kept awake at night by the wife listening to a low hum.

I will trawl the links, although a lot of them are about identified hums, whereas my problem is finding it.

Jim

Is it possible that the humming noise you hear is due to seasonal wind causing something to resonate?

If the problem continues you may want to look for new real estate.

Cheers

Joe

spinning roof vent?

I too sensitive to such hum sounds. Try this tonight:

Before going to bed plug all drain/ washbasin holes. You can put drain cap to wash basin, bathing tub etc. If your bathroom doors are tight, then close them. Some buildings the rain water pipe generates and carries hum and wash basins become loudspeakers. Or try to trace the origin of hum from drain hole of your apartment.

If the noise is intermittent,try to determine if it is associated with wind velocity or direction. All plumbing systems have vents that exit above the roof.They are generally large diameter pipes. If the wind direction is right, they can set up a low pitched hum like a reed on a very large flute.Does not have to be on your house, because low frequencies travel a long distance. Worth checking.

Oh by way,are there any elephants near by,like a zoo, or carnival, or circus? They communicate using VLF and use their feet as receptors.Nothing like an elephant with sleep apnea and somniloquy to keep the whole village awake.Were there any elephants at the festival? Perhaps they are still nearby,within a few miles? Their sub-audible tones can carry for many miles.

Good luck!

there is an elephant in the apartment above me!

have you checked the back lawn for elephants?

They when in the mating season emit a very low frequency hum to attract mates.

They are easy to miss if you're not looking for them

Well, I have seen them lumbering from pub to pub wearing tank tops, looking for a mate... but they were emitting high pitched shrieks.

I think the OP is in Derbyshire, so elephant infestation is absurd. The problem is undoubtedly down to it being the rutting season for wallabies.

Do you smell peanuts?

Turn loose a few lab mice, problem solved.

You mentioned the scarcity of air conditioners, but what about other devices that might use freon to either dehumidify or heat the air?

I have tracked down some of those annoying late night noises to freon lines that seem to circulate on their own after the mechanized cycle has stopped.

I would suggest a google for "low frequency noise". There are several symposiums and a host of references. I viewed a presentation on either Discovery Channel or NatGeo on the subject. There were said even 'recipients' that live in the middle of nowhere (boons) essentially that have been plagued.

A lot of theories, including tinitus.

Thanks for this Bill ML.

Since Chris admonished me for not searching the site I have googled various things also, and there is a wealth of info out there, but my mind is boggled at the moment. Except did you know that you can actually purchase 'Low Frequency Sound' for less on Ebay?

I have had the same thing happen when a power transformer (the ones on the power pole) was going bad. The hum was low freq (power line frequency) and was annoying, but you could only really hear it at night when most everything else was off. The problem eventually solved it's self when the transformer blew and they replaced it. I would suggest a directional mic to help track it down. You can make one from a moderately cone shaped pan and a simple microphone.

You may look for any high voltage transmission line passing where corona discharge may be producing the humming sound. This may not be heard in day time but surely could be heard at night.

If moma can't sleep .. you are in a quandary …... try some white noise.

You turned off the electrical power to the house & still had the hum. If you had a UPS power supply still on for the computer maybe its the hum source. I have seen generator sets that caused a hum in the ground that traveled hundreds of feet.

Good luck & let us know the cause when you find it.

Thanks doug, But no ups.After stepping outside in the night, Mrs is adamant it is louder outside.

Make yourself a portable "Hum" Detector.

A microphone, attached to a small amp, driving head phones.

When the mike is placed at the bottom of say a 2 foot long, 6" tube, the maximum gain will be when its pointing directly at the source......

GO HUNTIN'

Great idea, Andy.

There are things that make noises that do not penetrate the house, higher frequency ones, that mask the lower sounds which I can only just hear anyway. I guess this is where a low pass filter comes in.

This is reminiscent of the "Taos Hum", which has been plagueing residents for years. I found some .WAV examples on one of the BING results.

No source has ever been found that I know of.

WoodwardDL

I came across this one too. Like you say, no source ever found.

In the journal of low frequency noise, vibration and active control vol 28 no 1 2009,( Is there anything there isn't a trade magazine for?) I found 'How to find the source of low frequency noise: Three case studies by carl Ostendorf. Very interesting techniques of proof and elimination. A bit of a misnomer though, since in all three cases, NO SOURCE EVER FOUND

two words taht will solve your sleeping problems and remove the noise.

Drugs & plugs(ear)

Sorry chriss-288. The sample listed in post 19 has nothing to do about where the noise is coming from, only of how to get rid of it.

While I can understand your frustration of posts you may think have been discussed before, they take on a different direction when discussed and questioned, starting with a question.

My feeling of CR4 is that over the years, there have been many experienced gurus, you included, that are frustrated when someone asks the same question.

This is not a homework question (everyone pet peeve).

This person may be a new(?) user that does not know that one may research the past threads. The threads may not come up under his search.

This is a long rebuke, but I'm interested in this one and if you can't be constructive or at least funny, then don't post.

Karl Mavis (3 to 5 year reader)

Karl, you write extremely well for a 3-5 year old.......

Dear Karl,

New users are first directed to read the FAQ, and understand the process of posting. Located within that FAQ is this, whose first line is Look for answers before you post. I am just reiterating cr4 policy, as it was obviously missed first time around.

Also, google searches turn up extensive information, of which cr4 is not first on the list, nor the most comprehensive.

"if you can't be constructive or at least funny, then don't post." While this somewhat ironic for you to say, I also am interested in the subject, as I am sensitive to noise. I am obviously for my error for thinking this topic was previously thoroughly discussed, and I apologize for appearing to suggest the discussion be limited or ended.

Chris

it might be a little early to suggest this course of action, but have you thought about moving?

Who are you replying to, or do you mean EVERYONE on CR4?

Maybe we can blame it on global warming. This seems to the trend nowadays.

When you say "festival" is this with amusement rides requiring electrical power?

If so, was the power supplied by a gen-set or power grid?

If by power grid, was an existing transformer involved.

Were there any power problems noted during the time of the festival?

In the A/C units you mentioned, do any have modulated (speed controlled) condenser fans?

Yes exactly.

They were all powered from gen-sets. The living quarters for the crew were powered from the mains grid, plugged into a little used Council facility. In the past there used to be 240v cables all over the campsite, -100yds plus of ordinary extension cables. It looked to be 110v cables this year...am I thinking what you're thinking? A transformer has been left on in the facility..

there were no power problems during the festival.

I'll have a closer look at the A/C units in daylight. What are you thinking?

I based the questions concerning the festival on the possibility that a transformer had been temporally overloaded, which sometimes makes them noisy from that point on.

I mentioned the fan modulation because the fan motors can emit noise at lower speeds (such as, at night as the air temp lowers).

I apologize for asking so many questions, but I find it helps to get a clear picture and stimulates the desire to find an answer.

Have you considered Tinnitus. (not sure if the spelling is correct)

I have suddenly just started having issues with my ears. Can't figure out what triggered them to suddenly start the ringing. Guess its just an old age thing.

That would be a viable explanation if it was just Jim, or just his wife, but unless they've both been poisoned or exposed to very loud noise it is not likely that both would experience the same problem starting at the same time.

That's what I thought the wife had for a week, and I took no notice. Then she insisted that i listen, and there it was. At first only if I held my head right, but now I can pick it up more easily.
I have a high whistle all the time, I imagine it's wireless broadband, but it may not be

There was a thread on CR4 recently which described how to find the source of the noise, but, I cannot find it.

This assumes that the sound is in the air not structural. Essentially you put two microphones on the opposite ends of a long pole; amplify the signals and feed the results into two channels of an oscilloscope; rotate the pole until the two signals are coincident (time wise) on the display. Obviously you won't know if the signal is in front of you or behind you at this point so you may need to move "sideways" by a couple of hundred yards to work out which direction to follow.

Does this make sense, or, do I need to explain it more clearly?

Fascinating. Audio Triangulation of a source, with Phase adjustment. I'd love to see that thread, if you can find the link. But this certainly simplifies the process I tried to describe (very poorly, I'm afraid) much earlier in THIS thread. It also ADDS the very necessary, but completely overlooked by me, phase coincidence that pinpoints the source in one go.

GA to you!

Hmmm. I rethought this, after writing it. Since what I suggested you might be looking for is the two fundamental frequencies that could be creating a harmonic (your hum), and the harmonic is either a sum or difference of the two fundamentals, phase coincidence won't work. That would work only if you are looking for two signals with no appreciable difference in their frequencies. In that case, your "hum" would be what was commonly called a "zero-beat" frequency, in which case, the difference frequency (I'll deal with it as a sum in a few lines) would be so low as to approach zero hz. Still, the fundamentals would have to be different and distinct, though they would, in that case, be so close to identical as to allow for phase coincidence for short periods, with a tell-tale phase drift occurring. But that hum would not be a hum. It would literally be a thump, or, less often, for reasons of waveform attack and decay (leading and trailing edge of a pulse, respectively) a click.

It would not, at zero-beat harmonic frequencies, be a sum, solely because the two fundamentals to create a zero-beat signal would have to be each even nearer zero Hz than the audible thump, and those, being of necessity, at least twice the average amplitude of the thump, would at least be felt, if not heard as two additional thumps in the audio range.

Of course, everything I've said here and earlier presupposes that the harmonic, if it is such, is created from only two fundamental frequencies, and is what is called a "first order" harmonic. That would be a harmonic created directly from the two fundamentals, and not from a higher harmonic created from yet more fundamental frequencies. That, though, is a fairly safe supposition, once you accept the hum as a harmonic, because if it were a second or lower order harmonic, it would also be accompanied by a whole "audio soup" of other harmonics, all of which you'd also hear, with the result that your "hum" would be more like a Pickadilly Circus Traffic Jam (or Times Square, if you're in the US).

I believe your earlier suggestion (and Randall's and mine as well for that matter) does not take into account multi-path distortion.

I agree wholeheartedly. Oversight on my part, for sure. And I truly don't have an efficient suggestion for how to deal or discern that, or track it down. Does it phase-shift a signal by any appreciable amount (other than the obvious shift occurring over a longer path, I mean)? Does it frequency shift the signal? I would not expect it to do this, but then there are still way too many things I don't know about the subject.

I dunno, this is starting to get down in the weeds, but I'm thinking it is possible that this may be the result of the same source travelling via two different paths (one direct, one a reflection) and arriving at a slight phase difference resulting in a beat frequency.

That would only work if the indirect path length was being changed in some kind of repetitive way.

or if the sound source swept through a frequency range repetitively. then the phase difference would also result in a frequency difference as well.

Ah yes. That's beginning to sound (no pun intended) like a plausible scenario.

There was an omni-directional "pillar" speaker, that used concrete pipe as its resonant chamber, with the length of the pipe being 1/2 wavelength at the natural resonance of the woofer. Then, with the woofer firing upward from the upper edge of the pipe, and its backstroke firing downward, anyone sitting directly opposite any side of the pipe got an in-phase bass note at that frequency. The overall effect, if you have interest, was shown on an audio sweep scope to be nearly flat across the entire designed frequency range of the woofer/pipe combination. So, it would work to bend the path, for a single source, and have one portion of the source signal arrive directly, and the other by the bent path, to get the signals in phase. The only problem with this would be that, at 60 hz, the wavelength is roughly 1100 MILES. So a bent path to an in-phase signal would require an additional 550 or so miles of length added to the path by the bending. If the signal were at 6Khz, it would still take about half a mile of extra path. And at 60Khz, we wouldn't even hear the source.

Sorry. That was in response to 74, but I got it on to 77. My error.

Mach 1 is about 761.2 miles per hour, or about 0.21 miles per second (you know you count the time between lightening and thunder and divide by 5 to figure out how far away the lightening was). So the wavelength of 60 Hz would be about 18.61 ft.

But we're looking at an ultrasonic sound here (say 30 KHz) interfering with itself because of varying path lengths and frequency modulation so the wave lengths involved are around just less than half an inch. That would suggest to me that for this to be a possible explanation the reflecting surface must be something like a pretty big sheet of glass (just drivelling thinking out loud now really).

I know my brain is getting tired thinking so much, but I don't understand how your first paragraph, first half, leads to the conclusion about the wavelenght of a 60 Hz signal. I do know that I've calculated the wavelength for 60 Hz, to verify it, because when I was first told that, I goggled at the idea. But later, when I could not remember the formula (like now, though I know I could look it up), I passed a technical test in the US Navy, not least because I was able to remember that wavelength (it is approximate, but close enough for this purpose), and extrapolate the wavelength from that for a radar signal. But it may have actually been 2100 miles, now that I'm forced to think back on it. Certainly not mere (two-digit) feet.

But, please, don't make me go look it up and do the math here. My head already hurts.

The speed of light is ~186,000 miles per second, so an electromagnetic wave of frequency 60 Hz will have a wavelength of 186,000/60 = 3100 miles.

However we're talking about acoustic waves here: the speed of sound at sea level (Mach 1) is 761.2 miles per hour
that's 761.2X5280 = 4,019,136 feet per hour
which is 4,019,136/(60X60) = 1,116.4 feet per second
so an acoustic wave of frequency 60 Hz will have a wave length of 1,116.4/60 = 18.61 feet

Thank you. How I could have forgot the distinction, I do not know. I stand THOROUGHLY corrected, and appreciate your patience. My apology for being so obtuse.

Comment removed.

I had the same experience just a few years ago. It turns out that I had an fully cloaked alien space craft on my roof. I would talk to them, even though they never responded back, every night after midnight. I believe they thought that I could see them and finally left. My friend said he had the same problem with one hiding out in his swimming pool, which for some reason turned it green.

Just funnen...It sounds very much like a pole transformer or maybe your neighbor installed a new AC unit or pool pump.

I mentioned insect hums in a previous entry.

I found a few suspects and here is one in particular. Imagine several thousand of these bugs together mating (yipeekyyaa) and you will recognize a very loud bothersome noise often as a steady drone. You can find more insect noises here.

I'm on board with the portable hum detector. Or if you know someone with an oscilloscope you could also use that to analyze the frequency, waveshape, etc. and that should give you a clue.

Have you ever listened to a mains transformer closely? Is this the frequency you are hearing?

Heard a humming in my ears and compelled to revisit.

You guys have beat this one to death. Sorry, only my view.

Without any data there is nowhere to go. As yet I have no equipment that might do it, but tomorrow may bring some. I have checked all the things that don't require sound equipment, but nothing has shown up. Unfortunately I am working away during the day this week, so it's not so easy to chase things. I will post any developments of course. Thanks for your Help

Do not over look circulators pumps and AC/ refrigeration Equipment that might have been replaced /damage or moved.

I once had a service fitting that whistled when the unit operated.

We don't seem to be getting anywhere fast, lets try some simple tests.

On a quite evening when the noise is present & you can turn off the electrical service,take a screwdriver & place the handle against your ear & place the tip of the screwdriver against items that may be conducting the noise into the home.

Start by testing plumbing & structure. Test these items; drain waste vent pipes, Dryer vent pipes, rain water drain pipes, floor drains, hot & cold water pipes, water heater, water service pipe/meter,gas pipe/meter, furnace/air conditioning ducts, Furnace chimney,hose/sprinkler pipes, the cover of the electrical service Fuse/CB box. Test structural items; Basement floor & internal walls, external walls/windows/doors, support columns, main floor, main floor internal/external walls/ windows/doors, fireplace/wood stove & fireplace/stove ducting, Ceiling & ceiling access hatch... If you have a attached garage test every thing there also.

Now test all the appliances. icebox/freezer, air-conditioner, Waste disposal unit, gas stove. Sanitary fixtures...

The screwdriver test is a very good test when done correctly. Hold the screwdriver by the handle as near the ear as possible & don't touch the blade as this will dampen any sounds. You might want to practice on a noisy appliance first to develop your skill.

Some windows & pipes will only make noise when the wind is from a certain direction & speed. Windows might make noise if they are not completely closed & latched.

Get your spouse involved, her hearing may be more sensitive then yours & at least she will feel that you are serious about finding the source of the noise.

Good luck. I would very much like to know the answer to this problem.

Doug

Posidrive or ordinary Doug?. Thanks for the interest. I am currently awaiting a man from the Council with 'sophisticated sound measuring devices'. Of course they may be plugged into something much less sophisticated, and going by the speed of the action, they will be.

I have wandered round with a screwdriver before,.. oh, you put the handle in your ear, I thought it was painful, but picked up nothing. I will go round again, and send the wife round, her ears are more sensitive than mine...

Things aren't as bad as the first 2 weeks, not because we're getting used to the noise, but because we're getting used to lying awake and going without sleep

If it were Bangalore, I know the cause. We are long on festivals and short on power. We have a lot of such low frequency hum from unenclosed portable power generators.

Some of the lower cost standby inverters also generate such hum. Because these generate a square wave all fluorescent light chokes join in and add to the ruckus.

Bioramani

That's what we thought it was, a portable generator, but no...

I have just had a visit from a council person, after some prompting. He can hear the noise, or at least a low noise. He located it to exactly the same spot I did, a pipe exiting from a roof, despite that seeming to be an unlikely place. He is going to informally approach the owners of the property so as not to aggravate them by measuring it first.

He did come out with a story very similar to yours Micahd02, and I wondered if this was going to be a bit of bull****, but there were a few differences, including cloudcover affecting the noise, and finding the source when the factory shut down for vacation.

Progress.

I read somewhere the main problem with constant low frequency noise is that it evokes the fight or flight... 'It could be a threat, I don't know what should I do, it could be a threat what is it what should I do am I in danger,' this sort of response on a subconscious level, and it is the not knowing that keeps you alert when you should be asleep. When I said this to the wife, she slept better.

Knowledge is power

Also, talking to a neighbour in a nearby property, he said that during the time the festival was occurring, on two successive nights the main power feed into his building was disconnected, and his phones went dead for two days, and the phones did the same last year.

Also again, there have been several raids on properties locally that have been rented solely for the purpose of growing weed hydroponically. They tend to have fans and pumps going 24/7

Jim

I would suggest your councilperson bring along an IR scanner when the inspection is done. If this is a pot growng oporation, there will be a heat signature at that pipe which, if I suspect is an outake for heat from the lights, This pipe could be resonating at a low frequency.

Agreed, these things glow like a white hot star in IR. Also the water and electricity usage is off the charts too. 'round here the local volunteer fire departments have handheld thermal imaging systems to help find people in burning buildings that may be passed out from the fumes, or kids that hide from the flames under beds or in closets. These things can see a person through a hollow core door with lots of ambient heat noise. If your local fire crew has access to such an imager, perhaps it might pay to buy the crew a pitcher or two and ask them to give the flat in question a quick look-see with their IR camera. Might just kill two birds with one stone.

...well?? Did you ever find the hum, or did it simply stop??

The suspense is awful!