Mysterious Environmental Hum

Hey guys! Just recovering from a late summer c0uld and inflamed middle ear/s (there's 2 of them, right? Not actually a 3rd whole ear as such?). My hearing has been mostly down a few dB, but strangely UP in the bass. Particularly at about 77 Hz, and something has been making a rather steady tone at that frequency 24/7 and it has been driving me up the wall.

OK, I'm no professional like Clouseau, but I've been motivated to do some serious sleuthing. This is what I've got so far:

SPL: extremely low. Maybe 5 or 10dB above absolute zero. It easily fades and disappears momentarily with the onset of louder sounds, and if there's too much other noise I just won't hear it at all. It seems loudest at about 4 or 5am. Right in the middle of my beauty sleep!

Initially, I had to rule out mains electricity, so I switched off the breakers late at night. No fridge, no pumps or anything. I put the clock in a cupboard. No change.

Maybe it was tinnitus? Nope. From experience, that was usually some transient ringing that would shortly fade, and only on one side at a time. Or maybe a high frequency cicada like noise, but not constant bass in both ears.

I'd heard it before, but initially wrote it off as probably a water pump, so I put it out of my mind. But then we moved house, and then it dawned on me that the new place was producing the exact same sound from a year ago. As if the walls themselves were throbbing, and the tone seemed a bit louder if I was close to a wall or in a corner.

I haven't tried recording it yet. With my current non-setup it will likely be all noise and no signal, but it's coming.

I tried to pin-point the frequency by humming it and finding it on my keyboard, and eventually got a D# almost 2 octaves below middle C.

Then I found that if I played a D (natural) really softly with a mellow Rhodes-like sound and waited for the levels to balance out, I could get the two tones to interfere! Gotcha!!! The bastard!

Maybe it was underground mining or a factory or something nearby? The two houses are only a few km apart, so it still could have been a local source. But then I visited family over 40km away, and it was the same.

~~~
At this point, the only thing that seems to vaguely make sense is that it's a Schumann resonance of the earth (one of the harmonics anyway). But those are meant to be radio waves. Bizarre!
 
I was just reading up about it -- thanks for posting the link!

I made a couple more observations:
Yesterday I could hear it in a parked car, and it made no difference whether the windows were wound up or down. And I could hear it outside in a remote forest, quite far from town.

So I'm beginning to think it's some kind of radio stimulation, rather than actual air vibration. I was reading up about people doing scientific experiments, applying various forms of electrical stimulation to their ears, all the way back to Volta:
Chpt 15 "You mean you can hear electricity?"
In The Invisible Rainbow .
 
"The Hum" has been discussed before so read this thread for some tidbits.
https://www.diyaudio.com/community/threads/the-hum.317422/

As far as it concerns me I have gotten rid of the hum and tinnitus including most of a broad range of other autoimmune issues thanks to strict diet, intermittent fasting and the best attempt at suppressing stress, which is the least easy thing as there are factors in our lives which can't be escaped from, nowadays more than ever and for a reason.
 
But as far as I can tell, it's not internally generated, because of the ability to create tremolo 'beats' from interference with a similar frequency offset by a few Hertz.

I've never been quick enough to grab a keyboard and try that if a sporadic ring from tinnitus pops up out of nowhere. My suspicion there is that one specific nerve would start resonating with the brain, and nearby frequencies wouldn't be able to modulate it. So the software notices that something is 'off' and mutes it after a short while.
 
But as far as I can tell, it's not internally generated
That's what I also thought for many years which I also wrote in the older thread, I once invited a neighbor in the same house I lived in before (an old wooden house which was very quiet, I would only hear the thermostat controlled electric heater come on and off during the cold time of the year, but that was a rock steady 50 Hz mains hum not to be confused with "The Hum" I experienced back then) to have a listen in my apartment, I would hear the hum but my neighbor just shake the head. Another night I once sneak out to cut of the mains supply tho the whole darn house (apologies dear old neighbors to those it affected) and then crawled underneath it (can you even imagine how wacko that looked like.. ) as I wanted to find out if it was from the ground such as water pump etc., but nothing. The hum is very unreal in comparison to the high pitched tinnitus which is easy to locate as if coming from inside the ears because it really did sound like as if its source was exogenous, it's a totally unreal experience difficult to communicate with people about.
Today I am pretty convinced it is a form of disturbance in the auditory/nerve system, which in some cases could be explained with an underlying physiological and/or somatic health condition.

Are you sure it wasn't a 76 Hz signal? :-)
https://en.wikipedia.org/wiki/Project_Sanguine
 
By omitting "environmental" in the title you might get closer to your reality. Obviously you hear something which is not related to an outside-of-the-head sound source. My best guess ist that you might have a dysfunction of your hearing which might be located in your middle ear, as a sequel of your infection. As long as, in most cases, the noise is not synchronous with your hearth beat. In this latter case you would rather opt for a vessel anomaly in you head as the source of your hum.

Generally speaking, you can split the (in-head) auditory system related pathologic sound perceptions into two categories: high frequency pitched ones and low-frequency pitched ones. For high-frequency pitched phenomens the specialist will track down degenerative processes inside of the inner ear, typically such as tinnitus. Instead, low-frequency pitched phenomenons are related to anomalities in the middle or outer ear. So you will have to look there to track down your hum.

As for the outer ear, there are several possible causes for noise generation which has been described in the literature. E.g. typically a hair rubbing onto the tympanon. Or, more special, a colony of worms from an insect which clandestinly has deposited its clutch of eggs onto the cerumen inside of the auditory canal. And there are lots of other stories about outer ear's unwanted bells and whistles. If on medical inspection everything looks fine at the outer ear structures, then it's time to think about the middle ear.

The middle ear serves as some kind of a transformator station between the different impedances of the tympanon (air in outer ear / air in middle ear) and the foramen ovale (air in middle ear / liquor in the inner ear). This transformation is mechanically performed by three tiny bones, the malleus, the incus and the stapes. And two muscles, the m. tensor tympany and the m. stapedius do provide some adaptive damping of this transformation. E.g. the m.stapedius will instantly be tensed on loud incoming sound events, thus dampening the transmission.

As you certainly know from your own body, muscles are not always functioning as they should. You do suffer painful muscular cramps, and you certainly also observed less painful and transitory fibrillations or fasciculations of small muscle aeras under your skin. Now try to imagine what may happen to you hearing, if either one of these two middle-ear located muscles directly affecting the transformation of the impedance go berserk: If e.g the "bigger" tensor tympany breaks into fasciculations, then you will be annoyed by the perception of very, very loud and also painful banging, e.g. easily at an intensity subjectively above the hearing pain threshold. More subtle, e.g. if the stapedius breaks into a fibrillation ... there you are. You will be hearing som kind of a humming noise.

Such kind of hum might be annoying, even if it is very low intensity as in your case. So you may try to treat this, low-level by very generally optimizing muscular functionality. E.g. are you ok with your electrolytes? And try to rule out what may normally contribute to muscular cramps and the like. While doing so, try to keep staying on sound logical/medical grounds and don't waste your money for esoteric heil-promising approaches. And as long as it is low-level and not painful, you may pragmatically try cope with it (such is life ... we all are falling slowly apart while aging). There are several methods to improve the coping with such annoyances. Make your choice and try to find something that works best for you. I guess there are a lot of tips from serious and scientifically approved clinical trials with tinnitus patients (tinnitus because it is useless to treat and because it is widespread, only coping helps) for feasibly coping strategies.

Last not least try to enjoy audio anyway. And try not to bother too much about your unfortunate and intrinsic pathetic 30dB SNR.

Unless ...

... unless you better consult am otologist (probably once again, after your middle-ear infection, I guess?) for a competent final check and hopefully for a most probable "all-clear". Instead of relying on guesses, phantasms and advices from a random bunch of anonymous forum's gossippers (me included). It's concerning your head, finally. I underscore this because of the aforementionned vessel anomalies as a more exotic, but less trivial, possible cause. Despite the fact that you have a middle-ear infection anamnesis as probably a sequel and the most probable cause of this hum.
 
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Obviously you hear something which is not related to an outside-of-the-head sound source.
Ground vibrations could pass through solid objects, so I still haven't ruled that out. Interference patterns suggest that the level is tethered to real vibrations* : it's possible to cancel them out. The possibility of cramps is a fair point, but the frequency is exactly the same for both ears.

* Electrical stimulation of the cochlea could probably bypass most the mechanics, but it seems plausible that mechanical vibrations could still produce interference patterns.
 
Note to self: never mention health or medical stuff as background when discussing newfound superpowers or other scientific marvels.
diet, intermittent fasting
Big fan. I keep meaning to do a water fast, but they drag on and on, and quitting food for so many days is just so hard. I swear it's the deliciousness and FOMO more than actual hunger. I did a dry fast for a couple of days in the middle of a water fast and it actually seemed a lot easier.
 
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"Note to self: never mention health or medical stuff as background when discussing newfound superpowers or other scientific marvels."

Yup , Basic communications stuff. We take the words you use, to make the picture we would be describing if we were using those words, so if you're describing something outside our experience, no problem, we'll find a way to render it as something we already know . We're happy. : )