Frequency of the world wide humMysteries

The “Hum”

Do you hear it? When I moved to Ipswich, I began noticing an oscillating low frequency hum when I’m lying in bed at night, similar to a motor idling in the distance. Lately I’ve been hearing the hum again. My wife thinks it’s in my head and said I shouldn’t write this article. I’ve had high frequency tinnitus for as long as I can remember, but the hum is a very low frequency. I checked all of the obvious possibilities in and around my house, and it’s not a motor, the furnace, the dehumidifier or a transformer vibration.

So I Googled, and learned that “The Hum” is a worldwide phenomenon in which a distant rumbling sound is heard by about 2% of the population, which I guess makes me special. People who hear the hum describe a low-frequency sound inside their houses, around 20-40 hertz (the lower limit of normal human hearing). In industrial acoustics, it is well-established that wooden structures amplify frequencies below 100 Hz, even below 50 Hz. But that doesn’t explain the source of the hum.

I reproduced a 30 Hz frequency of the hum (without the modulations) at the Online Tone Generator.

Below is a recording of the hum in Windsor, Ontario.

Even Wikipedia has a page about “The Hum”:

“A name often given to widespread reports of a persistent and invasive low-frequency humming, rumbling, or droning noise not audible to all people. Hums have been widely reported by national media in the UK and the United States, and sometimes named according to the locality where the problem has been particularly publicized.”

The phenomenon has been studied for several decades with no definitive answers, but multiple explanations have been proposed:

  • The phenomenon is almost always heard inside a house. Some people tried switching off the main breaker but it made no difference.
  • Seismic hum is created by the Earth’s tectonic plate movements and volcanic eruptions.
  • Booming sand dunes can create sound during windy weather at a frequency between 70 and 110 Hz.
  • Ocean waves especially those located along shelf breaks can resonate with periods of 50 to 300 seconds through the ground and cause vibrations in nearby structures.
  • Infrasound, sound waves with a frequency below the lower limit of audibility (generally 20 Hz) must be sufficiently high to hear. Examples are diesel engines and wind turbines.
  • Electric hum around transformers by stray magnetic fields cause the enclosure and accessories to vibrate, typically at 50 hz, with harmonic tonal spikes at 100, 200, and 400Hz harmonic frequencies.
  • Power lines are known create a humming sound at line voltage frequency (120 / 240 Hz) with harmonic content above 50–60 Hz, aka “Mains Hum.”
  • Schumann resonances are continuous natural ELF waves resonating between the ionosphere and Earth’s surface at a frequency of 7.83 Hz, along with progressively weaker harmonics at 14.3, 20.8, 27.3 and 33.8 Hz.
  • Auditory perception of microwave pulses, which can create a wave of acoustic pressure conducted by the skull to the inner ear, activating the cochlea.
  • ELF (extremely low frequency) transmitters were proposed to communicate with submarines while submerged. Project Sanguine was a U.S. Navy project, proposed in 1968 and would have required a giant antenna covering two fifths of the state of Wisconsin, but was never implemented.
  • The VLF Transmitter Cutler in Cutler, Maine provides one-way communication to submarines in the Navy’s Atlantic Fleet at a frequency of 24 kHz and input power of up to 1.8 megawatts, one of the most powerful radio transmitters in the world
  • The US government’s High Frequency Active Auroral Research Program (HAARP) transmits RF into the ionosphere.
  • In northern latitudes, some people claim to hear the Aurora Borealis.
  • And of course, Aliens. But as I mentioned, I’m not crazy.

An example of how a beat is created with two different sound wave frequencies

It’s likely that the Hum is caused by a combination of two or more sources, which would explain why the perceived tone modulates irregularly. For example, have you ever pulled beside another vehicle at a traffic light and felt a pulsing vibration? That’s a phenomenon called a “beat,” when two sound waves with close frequencies interact with each other and create an amplitude modulation.

Two interfering sound frequencies create a beat
The purple and blue lines in the graph are individual sound frequencies. The yellow shaded areas represent the “beat” created by their interaction with each other and could explain why the “Hum” has irregular pulses.

The frequency difference between the two tones corresponds to the beating frequency. Multiple sources with close frequencies result in an irregular beat and variations in the sound amplitude (volume).

World-wide map of the Hum
Interactive world-wide map of the hum

In 1996 residents in Hull and Nahant, Massachusetts began reporting the unidentified sound of an engine idling in the distance. More recently, the World Hum Map produced by Dr. Glen MacPherson pinpoints hundreds of hum reports from the UK and the US, including reports from Topsfield, Newburyport, Salem and Gloucester.

Most “Hum hearers,” including myself, experience the Hum at a very low volume starting around 10 pm, and we don’t hear it during the day. Have you heard the Hum? I promise you’re not crazy!

References and further reading:

  1. Wikipedia: The Hum
  2. Wikipedia: Microseisms
  3. Denning, David, Journal of Scientific Exploration, Vol. 18, The Hum: An Anomalous Sound Heard Around the World
  4. Cracking the mystery of the ‘Worldwide Hum’
  5. Cat in the Shadows, the unexplained: What’s that noise?
  6. The New Republic: A Maddening Sound
  7. American Geophysical Union: Relative importance of the day‐night asymmetry in Schumann resonance amplitude records
  8. Robert Larsson, Vibration characterisation of low frequency engine idle vibrations
  9. The Atlantic: Why Everything Is Getting Louder

Categories: Mysteries

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27 replies »

  1. I never even knew about this until last month when I was in the UK. I thought I was hearing things or there was something wrong with me until I confirmed with someone else about the noise. Now I have something new to research.

    The strangest part of the hum for me was that I only heard it at night and in a couple of the rooms of the house it could be heard better.

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  2. I live in Del Mar California, and I started hearing it about 2 months ago. It sounds like different very low tones. I hear it starting between 8-10pm, and I often hear what sounds like a very loud idling noise between it. It’s very bizarre. Does anyone else live in San Diego and hear it??

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  3. Boca Raton, Florida. I hear it every night. Thought I was going mad. It’s so loud I thought the tv was on in the other room at first or that someone was in my attic. Confirmed those were not the case. Then I thought it was my neighbors tv. Our houses are not close but I went out side in the middle of the night to see if it was that and confirmed it wasn’t. It sounds like a constant rumbling sound with base Here and there. It starts are 9-10pm and continues until 8-9am. I can’t hear it during the day.

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  4. Hi! Im in Colorado Springs, Colorado and the humming is driving me crazy. No one else can hear it. I hear it mostly at night all the way into the morning. At first I thought it was the water heater or furnace because they are in my crawl space. I had technicians come to service them. It’s not the cause…there is nothing wrong and they are not making any sound. I did read up and found the gas line theory. There is a gas line right next to my home that could be the source. Either way, I’m annoyed.

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  5. Hear it as well and also nice to know I’m not the only one. Really noticed it months ago, so I started paying more attention to try and figure out what it was. Usually hear it late at night also. From Kansas

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  6. We here the hum in east Tx. We have lived here 16 yrs. At first we thought it was a truck idling .
    It is sometimes so loud and chages tones. My husband.says its coming from underground
    and he has mapped out 30 miles across that it can be heard.

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  7. I live in Newbury, MA and just started randomly hearing this and have been noticing it for about a week now. It’s the strangest thing and I can’t figure out where it’s coming from! I’m so glad I just stumbled across your article from nearby Ipswich!!!!

    Liked by 1 person

  8. I have the same problem , I live in Romania ..I hear it quite often at different intensity. The odd thing is that when i move around the room (and i can only hear it in my bedroom) i cant hear it in some places in the room ..but more like feel it. Like a vibration . I called over some of my neighbours as soon as it stared cause they wouldnt believe me and they heard it as well . So i might not be crazy . Feeling like a pressure in my head and getting headaches constantly..waking me up at night around 4am…Glad to found out that im not the only one but the fact that we cant indentify the source freaks me out. Some theories says “people that can hear the hum have low frequency and that intteracts with other low frequency around” ….🤦😓 I m really confused

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    • I had experienced this at an alarming rate in loudness and vibration for most of 2020. It was awful. But in desperation i prayed and God removed them and ive been free since november 2020..thank God!

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  9. I’m reading up on some of the stories around the internet. It could be possible that the noise comes from underground water/gas pipes coming into the house or drains. Water in the pipes is constantly moving and needs ventilation and moving air also makes a noise. Because it could be up to 6 feet deep it would change the sound frequency as it moves towards the house. People are also saying the humming keeps going after the main breaker is shut off so this may explain it. Just a thought.

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  10. I heard a rumbling hum about 5 months ago in April, I remember texting my bf about what I heard & even told my family but no one believed me. It was around 4am & i heard something that sounded like a plane flying, but I was raised & still live in Indianapolis, so I have heard planes, jets, factories, the highway traffic, every motor vehicle & knew there was a distinct difference in what I heard. I checked outside my window & opened it, there was no airplane above, no train or any sound like it. It was as if it was rumbling, but the sound didn’t echo or move away like everything I’ve heard before, it was very odd & disturbing so I googled what I heard, then started learning more about mysterious sounds. Skyquakes, earthquakes, tectonics, sound waves, polar shifting, solar sounds through the sky, the earth making noises. I found out that not everyone can hear it, that it remains unsolved. I listened to others recording sounds only a few are similar to what I heard. I’m still very confused & don’t know what to think!
    The only way I can describe it best is it being like the skyquake rumbling from some kind of force, it sounded as if it did come from the sky but I don’t know for sure, I just don’t know. However it does help to know that I am not alone, that’s it’s happening worldwide, for awhile it seemed as if I was person that believed it which made me feel crazy until I learned about it as much as I could. I believe the earth does make natural sounds that have to do with our solar system & galaxy, the earth is a traveling space ship following the sun towards the center, when I thought about it more & more. It does make you wonder about the prophecies foretold, the events happening globally, the virus, & so much more that we are only beginning to understand completely if ever!

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  11. I’ve had tinnitus for years. Many different sounds all at once. If in doubt, block both ears. If you still hear it, it’s you.

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    • I have tinnitus, but this sound is completely different. Tinnitus is high pitched like a ringing or a hiss sometimes more than one tone quality. But this is a low vibrating rumble that even has a physical sensation, like a pressure which can be attributed to a sonic boom effect. My tinnitus is with me all the time, this thing varies you can sometimes even hear it “approach ” around the same time in the evening. Its absolutely horrendous it gives me the creeps.

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      • Exactly the same here is nothing similar to tinnitus and the noise still gives me the creeps after many years of hearing it.

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  12. I have heard it as well (though I live in New Hampshire). Low frequency, late at night or early in the morning. I used to think a truck was idling somewhere nearby, but never saw one. It’s nice to know I’m not going crazy. Thanks.

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    • I hear the same . This been going on since July 2019 for me. Sometimes it last a hold week at a time. Very annoying. I live in Louisiana.

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  13. I first heard a hum at night when I was in my bedroom. It sounded to me as if it were coming from the ceiling/attic. I even called a friend to come over and listen. He couldn’t hear it. For me, the answer was that I am hearing my blood going through my veins/capillaries in my head/ear area.

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  14. Interesting. I hear a hum quite often, though it sounds like bees from afar…I do hear this in the day, though…I used to hear high frequency waves at night when I am in bed. I attributed it to my clock radio or other appliances…hmmmmmmmm, makes you wonder…

    Liked by 1 person

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