11 ms·

What is the mysterious 'global Hum' and is it simply noise pollution? (2019)

67 points by zeristor 6y ago

taneq 6y ago
It's an interesting story but the whole investigation seems rather slipshod. > “The bulk of the evidence suggests that the Hum is not an acoustic sound.” He explained: “This is indicated by the simple fact that most people do not hear it.” Surely it would be trivial to set up a sensitive microphone, record some samples when a "hum-hearer" says it's happening, and analyze the frequency spectrum? Instead they're just guessing that it's RF-related... but then the article goes on to discuss a bunch of sources of low frequency acoustic noise? > For instance, multiple Hum hearers, if in the same room together, will match the Hum to different acoustic frequencies. “That never, ever happens with standard acoustic sources, of any frequency. It just simply never happens,” he says. If only we had some kind of machine that could objectively measure acoustic frequencies... If it were high pitched, we'd write it off as tinnitus. If there's no low-pitched equivalent (is there?) then it's probably just a sampling of people who live within a block or two of someone with a high-powered subwoofer on their stereo.
- OneLeggedCat 6y ago
  > If there's no low-pitched equivalent (is there?) There is indeed low-pitch tinnitus. It's much less common. I have a version of it. In complete silence, I "hear" a rather pure 73 Hz tone. Luckily I am rarely in complete silence, or I think it would drive me crazy. A doctor said that I perhaps have inner ear damage that my brain has compensated for. I've had it for about a year. This is the tone: https://www.szynalski.com/tone-generator/#D2,v1 https://www.szynalski.com/tone-generator/#D2,v1
  - rleigh 6y ago
    Wow, that must be really annoying. I have it at a very high pitch. I did get it checked out, and inner ear or nerve damage was suggested as a cause. However, they also suggested that poor posture putting strain on the muscles around the neck could also be a factor, and I have noticed it gets worse when I slouch for extended periods. If you haven't investigated this side of things, it might be worth a go.
    - karmakaze 6y ago
      I was thinking that the 73 Hz tone is rather pleasant compared to the ~13kHz tone I hear/perceive in both ears almost constantly. It used to bother me a lot, now I accept its presence and try to focus on things I'm doing instead. Of course there's no knowing what the 73Hz experience is like when sustained. My high-pitched tone I attribute to a combination of exposure to loud live music and hypertension from coffee (and to a lesser extent alcohol). The intensity and pitch does vary and often something will trigger the start of the tone in the morning, like the sound of the towel hitting my ears when drying my hair. I've recently cut down my coffee intake dramatically.
      - OneLeggedCat 6y ago
        I think I agree with you. The low D note I hear must be more pleasant than the 13kHz you hear.
  - srtjstjsj 6y ago
    How do you know that's the frequency what you hear? Is it because when you add more 73Hz you don't notice it as much as adding other frequencies?
    - davidmurdoch 6y ago
      Other nearby tones will sound "out of tune". At least that's how I can find the pitch of my tinnitus.
    - OneLeggedCat 6y ago
      I "hear" the tone clearly. From that, I found this online tone generator, and experimented until it sounded nearly exactly like what I hear. I grew up around a lot of music, so maybe it's easier for me to pick out a tone.
  - teuobk 6y ago
    I've heard something similar for the past two years, except mine is at 78 Hz, and only in my left ear. As with you, I hear it only when it is extremely quiet. When the room ambient noise is above about 35 dBA, I never hear it. Also, oddly, it comes and goes over a scale of months, seemingly at random. One day, I'll wake up in my quiet bedroom and hear it, and I'll continue to hear it in quiet environments for a month or two. Then, after those several months, I'll wake up again and find it gone. I notice a very loose correlation to it abating after a loud weekend, like a weekend spent driving my race car or doing metal fabrication, but otherwise it seems random. A while back I ran it down with medical professionals, but the gist of that expensive adventure was that it was likely idiopathic. It appears to be of the subjective type rather than objective, but -- long story short -- that's not definitive. My "solution" for now is to run the ceiling fan at night during the months it's present.
    - hazeii 6y ago
      Very similar experience, after a bit of research it was clear the 'global hum' explanation loses out to the much simpler explanation that it's an internal effect. I too found exposure to loud noise supressed it (e.g. regularly suppressed for a couple of days after nightclubbing), also only 'audible' in very quiet surroundings (even lightly touching an earlobe caused the 'hum' to cut out). It went away after life got noisier (kids'n'dogs).
  - Razengan 6y ago
    How do you know the frequency of what you hear? Is it a guess or measurement?
    - OneLeggedCat 6y ago
      Another person asked this too. There's obviously no way to directly measure it, since it is simply a perception of something that does not actually exist. I only "hear" it because I have either neurological damage or inner ear damage. But I know musical notes, and it's a D2. A C#2 is too low, and a D#2 is way too high. It might be more like a 72Hz instead of 73Hz (D2), but it's close. It's a "guess" in the same way that any singer might sing any other particular note. I can hum it, in tune with itself, although the sound of my own voice destroys the perception. I can use that tone generator I linked above, starting it and stopping it, and compare until I hit the right note. Just like tuning a guitar by ear. I do have to have absolute quiet to hear it, but I can reliably hear it 100% of the time when in absolute quiet.
  - ddingus 6y ago
    I have experienced this after a long noisy drive and big change in elevation. For me, was closer to 50 60hz.
- jcims 6y ago
  I've heard a low pitched 'hum' for a couple of years now at my house. It is weird because it actually has two tones, one at ~28hz and one at ~36hz and it alternates between them...usually at the lower frequency but will sometimes hop up to the higher frequency for a few seconds. I've tried recording it with several different high quality microphone setups and absolutely nothing at all. Also, nobody in the house and none of my neighbors hear it. So at this point I think it's something in my head, but I only hear it when I'm in my house. Never when I'm on the road. Not sure if this counts as 'the hum' but it's definitely weird.
  - carlmr 6y ago
    How do you know the frequencies they're at? Did you Match it with sounds from your computer? What constitutes high quality microphones for you? Where these microphones that were made for this low frequency range? EDIT: Especially on the microphones maybe the actual noise isn't 28Hz, but the 28Hz are harmonics of a 14Hz, 7Hz, 3.5Hz,... vibration. These harmonics may get produced inside some structures near your ear, explaining why you hear it and others don't. You'd need special equipment to measure these low frequency vibrations.
    - jcims 6y ago
      Yes matching sounds on the computer. I can actually hear a beat when they are close but not exact. Mics were a variety of xlr and usb from rode, sennheiser and yeti over the past few years. Definitely in the frequency range but only moderate sensitivity at that freq and low to moderate self noise. Not exactly scientific but I would expect to see a bump of energy in the spectrum and get nothing.
      - carlmr 6y ago
        I'd be really intrigued whether you can find something at the harmonics using an infrasound microphone (some can measure down to 0.1Hz), but the price is probably prohibitive for an experiment.
        6y ago
- garyfirestorm 6y ago
  Yes you're absolutely right. I work in NVH dept at one of the car companies. We measure interior noise using mics which are accurate starting from below 20 Hz to 20 kHz. So this should be very trivial.
  - lph 6y ago
    One of the frustrating things about "the hum" that the article mentions is that, academically, it's been lumped into the lunatic fringe of conspiracy theories, and serious scientists aren't interested. It does seem like the right equipment and expertise should pretty easily be able to determine, conclusively, whether or not any given "hum" is a real physical sound.
    - garyfirestorm 6y ago
      In one of my old apartments, I was able to hear modulating pure tone low frequency noise on some nights. I definitely could tell the noise was perceptible only during night. I think there could be many reasons for this noise from water filtration plants, power plants, to any other large industrial applications.
- bigbubba 6y ago
  There is simply no way they forgot microphones exist. The obvious conclusion then is they did try microphones, detected nothing with them, then decided not to report this negative result.
withinboredom 6y ago
I nearly fell out of my couch laughing! I guess none of these people have ever lived on a boat. The hum is/are boats, you can hear them pretty far inland too, especially late at night!
- hombre_fatal 6y ago
  Feel free to update the wiki https://en.wikipedia.org/wiki/The_Hum https://en.wikipedia.org/wiki/The_Hum instead of squandering all that knowledge!
  - withinboredom 6y ago
    Ah that's a good idea. It doesn't bother me at all (since I know what it is, it's rather comforting and brings back good memories) but never considered that it might bother people who have no idea what it is (I've heard it as far as 20mi/30km away from a shipping lane in the US.) I live about 1mi/2km from a canal that regularly has barge traffic late at night. I'll see if I can find a mic or equipment that can pick up the hum, then do a little study. It'll be fun and also make it easy to reproduce around the world. Edit: I've also considered that the frequency could be a resonant frequency in the human body for some people, making it seem unnaturally loud. My wife can't hear it.
    - quicklime 6y ago
      > I've heard it as far as 20mi/30km away from a shipping lane in the US Have you taken a look at The World Hum Map (linked from the article)? There are a lot of data points that are deep inland, way more 30 kms. For example there points in the Australian outback, and all through the "flyover states" in the US.
      - withinboredom 6y ago
        I did, a lot of cities are near navigable rivers that barges go down. I don't think all hums are boats, but I'd be willing to venture that most near waterways are.
basicplus2 6y ago
I remember something on HN about large cooling systems for data centres being responsible for some of these hum noises, but i can't find the reference.
- adamjb 6y ago
  Could this be it? https://www.theatlantic.com/magazine/archive/2019/11/the-end-of-silence/598366/ https://www.theatlantic.com/magazine/archive/2019/11/the-end...
  - basicplus2 6y ago
    Yep! thats it, thanks!
- seattle_spring 6y ago
  My guess was cooling systems in general. I lived uphill from a residential complex and the units on the roof pointed directly at my house. The hum drove me nuts, but it was below any legal noise threshold. It was louder inside my house than outside.
  - garyfirestorm 6y ago
    Yes resonances are a fun thing. For very little vibration input, you could get exceptionally large acoustic output.
thinkingemote 6y ago
I wonder whether people heard the hum more or less, quieter or louder during the lockdown when everything was so much quieter. Anyone know of any change? I've heard the hum many times in different parts of the UK and its usually loudest on bank holidays - that is, the days when things are most quiet. I think I'm hearing my own blood pumping away - a kind of merged drum beat. Now - I have also heard the associated "Hummadruz" too - which is more of an insect / bee drone. I recorded it on my camera but the audio couldn't pick it up. However I was walking though a field where there were many foxgloves, dry stone walls and bees around in high summer. Non hive bees will often live and buzz in their holes, so the hummadruz could be literally insects. The low bassy drone in both the hum and the hummadruz makes it hard to pin point the direction - it's why you only need one bass speaker in most hi fi systems.
- lph 6y ago
  I started hearing a hum in March, coinciding perfectly with my shift to working from home during lockdown. Glen MacPherson (who runs the hum database) has also reported a surge in hum reports.
- yetihehe 6y ago
  > Now - I have also heard the associated "Hummadruz" too - which is more of an insect / bee drone. I hate mosquitoes, but mainly their sound. Sometimes when it's pretty silent, I can hear mosquito like it was in a room (with pitch varied like real mosquitoes) but it's entirely in my head (like tinnitus, I have it sometimes when air pressure changes), I found out when I've tried to cover my ears and sound didn't stop. I've already already learned to distinguish between real ones, imaginary ones and TIR's on nearby road (which simetimes sound similar).
deleted 6y ago
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Pick-A-Hill2019 6y ago
I was curious to see if it might be related to something called Schumann resonances since there are three harmonics that fall in to the range of human hearing at 20.8, 27.3 and 33.8 Hz [1]. I doubt that it would ever be strong enough to be perceived by the human ear but if the ionosphere can act as a wave-guide at those frequencies (20 and 40 Hz) then a fairly distant but loud noise could conceivably 'bounce' the sound hundreds or thousands of miles and 'hearing' it would depend on a) being at the exact location that the sound wave bounced down, b) ideal atmospheric conditions, c) being able to hear low frequency sounds and or d) having something inside a house that develops a sympathetic resonance. Slightly plausible but highly unlikely but it did lead me to https://en.wikipedia.org/wiki/List_of_unexplained_sounds https://en.wikipedia.org/wiki/List_of_unexplained_sounds which made the thought experiment worthwhile. [1] https://en.wikipedia.org/wiki/Schumann_resonances https://en.wikipedia.org/wiki/Schumann_resonances
angel_j 6y ago
4% of the population is small enough to represent people with extra sensitive hearing, or bigger ears. They could be hearing many different sources of low frequencies (long wavelengths), which have high resonance ergo long range. The most general (worldwide) sources I can think of would be high altitude wind, or subterranean water flow. I heard the hum, middle of last night, after two days heavy rain, and I live over a large watershed. I have sensitive hearing and big ears. The study should also ask people to rate their motion sensitivity.
egypturnash 6y ago
I have dealt with hearing a Hum and it is super frustrating. Near the end of my time living in Seattle, something started making a hum. It was loud, and deep, and penetrating. Miserably loud - and yet my SO, who was visiting the day it started, heard nothing. I went on a trip the next day and it persisted for a while in my head, but stopped the next morning, and I spent a hum-free weekend. Then I came home and it wasn't quite as loud as it originally was, but it was still there. Most annoyingly, it was there in my bedroom at night. My SO never heard it. I kept on questioning my sanity. Sometimes I could hear it in other quiet parts of town. There were times I'd go into a favorite coffee shop to work and turn right around, because the hum was strong in there. I'd generally stop hearing it if I left my neighborhood. And every time I'd go on a trip? Nothing. No hum. Even in the middle of the night. But the fact that only I seemed to hear it kept making me wonder - is something wrong with my ears? Or do I just have a range of hearing that extends lower than most people? I got in the habit of wearing earplugs at night and using noise generators to somewhat block it out (hooray for mynoise.net) via a small iPad sitting under my pillow while I slept with the ear that heard it the most, but I still had a lot of trouble sleeping. Sometimes I'd try sleeping in one of the other rooms to get away from it a little. And then, after about a year or two of misery because I could never get a good night's sleep, I moved to a different city entirely. It's gone. I've almost forgotten what it was like to live with that oppressive, constant, maddening noise that nobody else heard. Every now and then I'm reminded of that and I am super grateful that it's gone. My suspicion was always that it was something to do with the subway expansion, my apartment was right above the line being dug north from the University District. Some ventilation fan that was making a noise that reverberated through the ground and came up in my ground-floor bedroom. I'll never know. I did a lot of reading about these sorts of things during this period. Some Hums get found: The sound of a thousand air conditioner fans droning 24-7 to keep a data center cool. A misaligned pump. Fish mating calls. These are all things that a Hum has been verifiably traced to, and stopped. Some Hums never get found. And it's fucking maddening because everyone you talk to about it is all "maybe it's just tinnitus" even though it stops when you go somewhere else.
- andi999 6y ago
  Forget about the stops if you go somewhere else. If you put earplugs (finger) in your ear and volume goes down then it is external.
Barrin92 6y ago
isn't it also quite possible that there simply is no external source at all and this is just some kind of disease like a tinnitus? Tinnitus is quite common with IIRC 15-20% of people having it to some degree, so the 4% of people reporting hearing the hum seems possible. Maybe it's more common in urban areas because people in urban areas suffer more from loud noise pollution.
bagels 6y ago
Sometimes it's just boring industrial noise pollution. https://www.npr.org/2020/08/04/898853311/it-took-a-pandemic-mystery-of-windsor-hum-is-solved https://www.npr.org/2020/08/04/898853311/it-took-a-pandemic-...
chrispeel 6y ago
For many, I think the "global Hum" is too much caffeine :-) See https://www.audible.com/pd/Caffeine-Audiobook/B083MVZ91Y https://www.audible.com/pd/Caffeine-Audiobook/B083MVZ91Y
davidhyde 6y ago
> “Moreover, despite a number of reports, MacPherson is not convinced the Hum has ever been recorded, even by sophisticated audio equipment.” I found this to be the most relevant part of the article. There was a side investigation into electromagnetic effects but this was disproven with a faraday cage. So... this “mystery” seems to be plain old tinnitus, albeit a low frequency version.
mikhailfranco 6y ago
Maybe we should start worrying when the hum stops: The Machine Stops - E.M.Forster https://en.wikipedia.org/wiki/The_Machine_Stops https://en.wikipedia.org/wiki/The_Machine_Stops
warpspin 6y ago
By now, it should be pretty much well known that the hum is produced by the Caponians in their effort to subdue humanity: https://en.wikipedia.org/wiki/Zak_McKracken_and_the_Alien_Mindbenders https://en.wikipedia.org/wiki/Zak_McKracken_and_the_Alien_Mi...

67 points by zeristor 6y ago

It's an interesting story but the whole investigation seems rather slipshod. > “The bulk of the evidence suggests that the Hum is not an acoustic sound.” He explained: “This is indicated by the simple fact that most people do not hear it.” Surely it would be trivial to set up a sensitive microphone, record some samples when a "hum-hearer" says it's happening, and analyze the frequency spectrum? Instead they're just guessing that it's RF-related... but then the article goes on to discuss a bunch of sources of low frequency acoustic noise? > For instance, multiple Hum hearers, if in the same room together, will match the Hum to different acoustic frequencies. “That never, ever happens with standard acoustic sources, of any frequency. It just simply never happens,” he says. If only we had some kind of machine that could objectively measure acoustic frequencies... If it were high pitched, we'd write it off as tinnitus. If there's no low-pitched equivalent (is there?) then it's probably just a sampling of people who live within a block or two of someone with a high-powered subwoofer on their stereo.

OneLeggedCat 6y ago
> If there's no low-pitched equivalent (is there?) There is indeed low-pitch tinnitus. It's much less common. I have a version of it. In complete silence, I "hear" a rather pure 73 Hz tone. Luckily I am rarely in complete silence, or I think it would drive me crazy. A doctor said that I perhaps have inner ear damage that my brain has compensated for. I've had it for about a year. This is the tone: https://www.szynalski.com/tone-generator/#D2,v1 https://www.szynalski.com/tone-generator/#D2,v1
- rleigh 6y ago
  Wow, that must be really annoying. I have it at a very high pitch. I did get it checked out, and inner ear or nerve damage was suggested as a cause. However, they also suggested that poor posture putting strain on the muscles around the neck could also be a factor, and I have noticed it gets worse when I slouch for extended periods. If you haven't investigated this side of things, it might be worth a go.
  - karmakaze 6y ago
    I was thinking that the 73 Hz tone is rather pleasant compared to the ~13kHz tone I hear/perceive in both ears almost constantly. It used to bother me a lot, now I accept its presence and try to focus on things I'm doing instead. Of course there's no knowing what the 73Hz experience is like when sustained. My high-pitched tone I attribute to a combination of exposure to loud live music and hypertension from coffee (and to a lesser extent alcohol). The intensity and pitch does vary and often something will trigger the start of the tone in the morning, like the sound of the towel hitting my ears when drying my hair. I've recently cut down my coffee intake dramatically.
    - OneLeggedCat 6y ago
      I think I agree with you. The low D note I hear must be more pleasant than the 13kHz you hear.
- srtjstjsj 6y ago
  How do you know that's the frequency what you hear? Is it because when you add more 73Hz you don't notice it as much as adding other frequencies?
  - davidmurdoch 6y ago
    Other nearby tones will sound "out of tune". At least that's how I can find the pitch of my tinnitus.
  - OneLeggedCat 6y ago
    I "hear" the tone clearly. From that, I found this online tone generator, and experimented until it sounded nearly exactly like what I hear. I grew up around a lot of music, so maybe it's easier for me to pick out a tone.
- teuobk 6y ago
  I've heard something similar for the past two years, except mine is at 78 Hz, and only in my left ear. As with you, I hear it only when it is extremely quiet. When the room ambient noise is above about 35 dBA, I never hear it. Also, oddly, it comes and goes over a scale of months, seemingly at random. One day, I'll wake up in my quiet bedroom and hear it, and I'll continue to hear it in quiet environments for a month or two. Then, after those several months, I'll wake up again and find it gone. I notice a very loose correlation to it abating after a loud weekend, like a weekend spent driving my race car or doing metal fabrication, but otherwise it seems random. A while back I ran it down with medical professionals, but the gist of that expensive adventure was that it was likely idiopathic. It appears to be of the subjective type rather than objective, but -- long story short -- that's not definitive. My "solution" for now is to run the ceiling fan at night during the months it's present.
  - hazeii 6y ago
    Very similar experience, after a bit of research it was clear the 'global hum' explanation loses out to the much simpler explanation that it's an internal effect. I too found exposure to loud noise supressed it (e.g. regularly suppressed for a couple of days after nightclubbing), also only 'audible' in very quiet surroundings (even lightly touching an earlobe caused the 'hum' to cut out). It went away after life got noisier (kids'n'dogs).
- Razengan 6y ago
  How do you know the frequency of what you hear? Is it a guess or measurement?
  - OneLeggedCat 6y ago
    Another person asked this too. There's obviously no way to directly measure it, since it is simply a perception of something that does not actually exist. I only "hear" it because I have either neurological damage or inner ear damage. But I know musical notes, and it's a D2. A C#2 is too low, and a D#2 is way too high. It might be more like a 72Hz instead of 73Hz (D2), but it's close. It's a "guess" in the same way that any singer might sing any other particular note. I can hum it, in tune with itself, although the sound of my own voice destroys the perception. I can use that tone generator I linked above, starting it and stopping it, and compare until I hit the right note. Just like tuning a guitar by ear. I do have to have absolute quiet to hear it, but I can reliably hear it 100% of the time when in absolute quiet.
- ddingus 6y ago
  I have experienced this after a long noisy drive and big change in elevation. For me, was closer to 50 60hz.
jcims 6y ago
I've heard a low pitched 'hum' for a couple of years now at my house. It is weird because it actually has two tones, one at ~28hz and one at ~36hz and it alternates between them...usually at the lower frequency but will sometimes hop up to the higher frequency for a few seconds. I've tried recording it with several different high quality microphone setups and absolutely nothing at all. Also, nobody in the house and none of my neighbors hear it. So at this point I think it's something in my head, but I only hear it when I'm in my house. Never when I'm on the road. Not sure if this counts as 'the hum' but it's definitely weird.
- carlmr 6y ago
  How do you know the frequencies they're at? Did you Match it with sounds from your computer? What constitutes high quality microphones for you? Where these microphones that were made for this low frequency range? EDIT: Especially on the microphones maybe the actual noise isn't 28Hz, but the 28Hz are harmonics of a 14Hz, 7Hz, 3.5Hz,... vibration. These harmonics may get produced inside some structures near your ear, explaining why you hear it and others don't. You'd need special equipment to measure these low frequency vibrations.
  - jcims 6y ago
    Yes matching sounds on the computer. I can actually hear a beat when they are close but not exact. Mics were a variety of xlr and usb from rode, sennheiser and yeti over the past few years. Definitely in the frequency range but only moderate sensitivity at that freq and low to moderate self noise. Not exactly scientific but I would expect to see a bump of energy in the spectrum and get nothing.
    - carlmr 6y ago
      I'd be really intrigued whether you can find something at the harmonics using an infrasound microphone (some can measure down to 0.1Hz), but the price is probably prohibitive for an experiment.
      - 6y ago
garyfirestorm 6y ago
Yes you're absolutely right. I work in NVH dept at one of the car companies. We measure interior noise using mics which are accurate starting from below 20 Hz to 20 kHz. So this should be very trivial.
- lph 6y ago
  One of the frustrating things about "the hum" that the article mentions is that, academically, it's been lumped into the lunatic fringe of conspiracy theories, and serious scientists aren't interested. It does seem like the right equipment and expertise should pretty easily be able to determine, conclusively, whether or not any given "hum" is a real physical sound.
  - garyfirestorm 6y ago
    In one of my old apartments, I was able to hear modulating pure tone low frequency noise on some nights. I definitely could tell the noise was perceptible only during night. I think there could be many reasons for this noise from water filtration plants, power plants, to any other large industrial applications.
bigbubba 6y ago
There is simply no way they forgot microphones exist. The obvious conclusion then is they did try microphones, detected nothing with them, then decided not to report this negative result.

withinboredom 6y ago

I nearly fell out of my couch laughing! I guess none of these people have ever lived on a boat. The hum is/are boats, you can hear them pretty far inland too, especially late at night!

hombre_fatal 6y ago
Feel free to update the wiki https://en.wikipedia.org/wiki/The_Hum https://en.wikipedia.org/wiki/The_Hum instead of squandering all that knowledge!
- withinboredom 6y ago
  Ah that's a good idea. It doesn't bother me at all (since I know what it is, it's rather comforting and brings back good memories) but never considered that it might bother people who have no idea what it is (I've heard it as far as 20mi/30km away from a shipping lane in the US.) I live about 1mi/2km from a canal that regularly has barge traffic late at night. I'll see if I can find a mic or equipment that can pick up the hum, then do a little study. It'll be fun and also make it easy to reproduce around the world. Edit: I've also considered that the frequency could be a resonant frequency in the human body for some people, making it seem unnaturally loud. My wife can't hear it.
  - quicklime 6y ago
    > I've heard it as far as 20mi/30km away from a shipping lane in the US Have you taken a look at The World Hum Map (linked from the article)? There are a lot of data points that are deep inland, way more 30 kms. For example there points in the Australian outback, and all through the "flyover states" in the US.
    - withinboredom 6y ago
      I did, a lot of cities are near navigable rivers that barges go down. I don't think all hums are boats, but I'd be willing to venture that most near waterways are.

basicplus2 6y ago

I remember something on HN about large cooling systems for data centres being responsible for some of these hum noises, but i can't find the reference.

adamjb 6y ago
Could this be it? https://www.theatlantic.com/magazine/archive/2019/11/the-end-of-silence/598366/ https://www.theatlantic.com/magazine/archive/2019/11/the-end...
- basicplus2 6y ago
  Yep! thats it, thanks!
seattle_spring 6y ago
My guess was cooling systems in general. I lived uphill from a residential complex and the units on the roof pointed directly at my house. The hum drove me nuts, but it was below any legal noise threshold. It was louder inside my house than outside.
- garyfirestorm 6y ago
  Yes resonances are a fun thing. For very little vibration input, you could get exceptionally large acoustic output.

thinkingemote 6y ago

I wonder whether people heard the hum more or less, quieter or louder during the lockdown when everything was so much quieter. Anyone know of any change? I've heard the hum many times in different parts of the UK and its usually loudest on bank holidays - that is, the days when things are most quiet. I think I'm hearing my own blood pumping away - a kind of merged drum beat. Now - I have also heard the associated "Hummadruz" too - which is more of an insect / bee drone. I recorded it on my camera but the audio couldn't pick it up. However I was walking though a field where there were many foxgloves, dry stone walls and bees around in high summer. Non hive bees will often live and buzz in their holes, so the hummadruz could be literally insects. The low bassy drone in both the hum and the hummadruz makes it hard to pin point the direction - it's why you only need one bass speaker in most hi fi systems.

lph 6y ago
I started hearing a hum in March, coinciding perfectly with my shift to working from home during lockdown. Glen MacPherson (who runs the hum database) has also reported a surge in hum reports.
yetihehe 6y ago
> Now - I have also heard the associated "Hummadruz" too - which is more of an insect / bee drone. I hate mosquitoes, but mainly their sound. Sometimes when it's pretty silent, I can hear mosquito like it was in a room (with pitch varied like real mosquitoes) but it's entirely in my head (like tinnitus, I have it sometimes when air pressure changes), I found out when I've tried to cover my ears and sound didn't stop. I've already already learned to distinguish between real ones, imaginary ones and TIR's on nearby road (which simetimes sound similar).

deleted 6y ago

[deleted]

Pick-A-Hill2019 6y ago

I was curious to see if it might be related to something called Schumann resonances since there are three harmonics that fall in to the range of human hearing at 20.8, 27.3 and 33.8 Hz [1]. I doubt that it would ever be strong enough to be perceived by the human ear but if the ionosphere can act as a wave-guide at those frequencies (20 and 40 Hz) then a fairly distant but loud noise could conceivably 'bounce' the sound hundreds or thousands of miles and 'hearing' it would depend on a) being at the exact location that the sound wave bounced down, b) ideal atmospheric conditions, c) being able to hear low frequency sounds and or d) having something inside a house that develops a sympathetic resonance. Slightly plausible but highly unlikely but it did lead me to https://en.wikipedia.org/wiki/List_of_unexplained_sounds https://en.wikipedia.org/wiki/List_of_unexplained_sounds which made the thought experiment worthwhile. [1] https://en.wikipedia.org/wiki/Schumann_resonances https://en.wikipedia.org/wiki/Schumann_resonances

angel_j 6y ago

4% of the population is small enough to represent people with extra sensitive hearing, or bigger ears. They could be hearing many different sources of low frequencies (long wavelengths), which have high resonance ergo long range. The most general (worldwide) sources I can think of would be high altitude wind, or subterranean water flow. I heard the hum, middle of last night, after two days heavy rain, and I live over a large watershed. I have sensitive hearing and big ears. The study should also ask people to rate their motion sensitivity.

egypturnash 6y ago

I have dealt with hearing a Hum and it is super frustrating. Near the end of my time living in Seattle, something started making a hum. It was loud, and deep, and penetrating. Miserably loud - and yet my SO, who was visiting the day it started, heard nothing. I went on a trip the next day and it persisted for a while in my head, but stopped the next morning, and I spent a hum-free weekend. Then I came home and it wasn't quite as loud as it originally was, but it was still there. Most annoyingly, it was there in my bedroom at night. My SO never heard it. I kept on questioning my sanity. Sometimes I could hear it in other quiet parts of town. There were times I'd go into a favorite coffee shop to work and turn right around, because the hum was strong in there. I'd generally stop hearing it if I left my neighborhood. And every time I'd go on a trip? Nothing. No hum. Even in the middle of the night. But the fact that only I seemed to hear it kept making me wonder - is something wrong with my ears? Or do I just have a range of hearing that extends lower than most people? I got in the habit of wearing earplugs at night and using noise generators to somewhat block it out (hooray for mynoise.net) via a small iPad sitting under my pillow while I slept with the ear that heard it the most, but I still had a lot of trouble sleeping. Sometimes I'd try sleeping in one of the other rooms to get away from it a little. And then, after about a year or two of misery because I could never get a good night's sleep, I moved to a different city entirely. It's gone. I've almost forgotten what it was like to live with that oppressive, constant, maddening noise that nobody else heard. Every now and then I'm reminded of that and I am super grateful that it's gone. My suspicion was always that it was something to do with the subway expansion, my apartment was right above the line being dug north from the University District. Some ventilation fan that was making a noise that reverberated through the ground and came up in my ground-floor bedroom. I'll never know. I did a lot of reading about these sorts of things during this period. Some Hums get found: The sound of a thousand air conditioner fans droning 24-7 to keep a data center cool. A misaligned pump. Fish mating calls. These are all things that a Hum has been verifiably traced to, and stopped. Some Hums never get found. And it's fucking maddening because everyone you talk to about it is all "maybe it's just tinnitus" even though it stops when you go somewhere else.

andi999 6y ago
Forget about the stops if you go somewhere else. If you put earplugs (finger) in your ear and volume goes down then it is external.

Barrin92 6y ago

isn't it also quite possible that there simply is no external source at all and this is just some kind of disease like a tinnitus? Tinnitus is quite common with IIRC 15-20% of people having it to some degree, so the 4% of people reporting hearing the hum seems possible. Maybe it's more common in urban areas because people in urban areas suffer more from loud noise pollution.

bagels 6y ago

Sometimes it's just boring industrial noise pollution. https://www.npr.org/2020/08/04/898853311/it-took-a-pandemic-mystery-of-windsor-hum-is-solved https://www.npr.org/2020/08/04/898853311/it-took-a-pandemic-...

chrispeel 6y ago

For many, I think the "global Hum" is too much caffeine :-) See https://www.audible.com/pd/Caffeine-Audiobook/B083MVZ91Y https://www.audible.com/pd/Caffeine-Audiobook/B083MVZ91Y

davidhyde 6y ago

> “Moreover, despite a number of reports, MacPherson is not convinced the Hum has ever been recorded, even by sophisticated audio equipment.” I found this to be the most relevant part of the article. There was a side investigation into electromagnetic effects but this was disproven with a faraday cage. So... this “mystery” seems to be plain old tinnitus, albeit a low frequency version.

mikhailfranco 6y ago

Maybe we should start worrying when the hum stops: The Machine Stops - E.M.Forster https://en.wikipedia.org/wiki/The_Machine_Stops https://en.wikipedia.org/wiki/The_Machine_Stops

warpspin 6y ago

By now, it should be pretty much well known that the hum is produced by the Caponians in their effort to subdue humanity: https://en.wikipedia.org/wiki/Zak_McKracken_and_the_Alien_Mindbenders https://en.wikipedia.org/wiki/Zak_McKracken_and_the_Alien_Mi...