Comment by taneq | Hacker News Reader

Comment by taneq | Hacker News Reader

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.

> 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

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.

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.

I think I agree with you. The low D note I hear must be more pleasant than the 13kHz you hear.

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?

Other nearby tones will sound "out of tune". At least that's how I can find the pitch of my tinnitus.

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.

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.

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).

How do you know the frequency of what you hear? Is it a guess or measurement?

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.

I have experienced this after a long noisy drive and big change in elevation. For me, was closer to 50 60hz.

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.

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.

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.

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.

That's the next step, just have some other projects to get out of the way first. There's a fairly low cost infrasound recording option using loudspeakers[1] that I think is worth a try. I'm also interested in building a seismograph, which might be able to pick it up on the high end of its range. If the sound is anywhere as loud as I hear it, there isn't much need for anything ultra-sensitive.

[1] https://www.youtube.com/watch?v=mekmsgjSqR4

I actually plan on recording sounds from my head, too. Could be weird spasms or something causing it, the lack of any variation in the two pitches makes that seem unlikely but possible.

Saw some interesting research on using infrasound to locate elephants. they managed to come up with something that was about $9 in parts including microphone. (Plus a SBC for analysis).

A bit of searching lead to some DIY stuff using subwoofers (speakers) as the microphone input then some low-pass filtering and then fed to an op-amp.

Here's the link to the research paper on the elephant detector https://www.researchgate.net/publication/320596116_Eloc_Loca...

Yeah you'd need PCB mics with reference level sensitivity. They cost over 800$ and the equipment that measures the noise costs in thousands.

I wonder if fans with (not a power of 2) blades could also generate surprising tonal (i.e., not transient) frequencies.

I could imagine this logic also applying to other pumps in the house: AC pumps, baseboard heat circulators, sump pumps, etc.

They might be able to do it with an Earthworks M30 measurement mic, which claims accuracy down to 3 Hz, and an appropriate digitizer. It's expensive but not as blisteringly expensive as lab mics like Brüel & Kjær's gear.

I heard an annoying hum out in the wilderness of Charlo MT that nobody else could hear, but chalked it up to radio equipment because there WAS actually a large tower nearby, that could be explained as part of a hi-def video streaming operation to capture these lovelies, just "next door" aka within a few miles.

Charlo Osprey Cam: https://explore.org/livecams/ospreys/charlo-montana-osprey-n...

I assumed there was some heavy duty radio equipment to handle this but was never really able to confirm the source of the noise, I was visiting for a couple of months two years ago. There were days when I just could not tune it out, and there were days when I either didn't notice it at all, or it wasn't present.

Towers can generate noise all by themselves in moving air through vortex shedding.

Perhaps you've already considered this, but could it be caused by a fan or some other source of mechanical vibration in your house? Acoustic propagation within a house can be surprisingly complicated.

Some years ago I noticed a very strange hum in one corner of my basement. Thanks to funky acoustics, I couldn't identify the source for a while, but IIRC it ended up being a fan in another part of the house. I suspect most of the energy traveled through the house framing, and ended up resonating in the room I was in at the time.

It’s very possible. There’s another source of noise that I’ve noticed, it’s qualitatively different so I don’t think it’s related, but there is a life flight helicopter pad about 2 miles from me. Every now and then there will be a real low rumble in the house that you can actually feel more than hear. About a minute later the helicopter will fly overhead.

There is an auto assembly plant about 5 miles away, if it’s not in my head it’s almost certainly something from there. The ground here has a extremely high clay content, and when you get down a bit it’s like one solid mass. It seems ideal for transmitting sound long distances.

Perhaps you could clamp a microphone to a metal rod stuck into the Earth to test that hypothesis.

Same for clamping onto the structure of your house for the vibration/fan one?

Finally, if all else fails, clamp a microphone to your head

If you have enough time when you notice the sound, it might be interesting to turn off your house's main circuit breaker to see if the sound goes away. Might be a quick way to bisect the analysis.

Ah! Now that you mention it, I have done that. It didn’t make a difference and I think that is roughly when I started seriously considering this was all in my head.

I can see why that possibility would drive you nuts!

Then I second the idea of getting two recordings (baseline and when you hear this) using a suitable mic. If you can afford the hardware, it's got to be way cheaper than questioning your hearing and/or psyche for the rest of your life :)

Definitely worth trying! Thanks for the ideas and the support, 2020 isn't the best year for 'hearing weird things at home' haha :)

Glad to be a sounding board. Yeah, 2020 is definitely the year we could write the book, "Gaslighting Yourself for Dummies". Best of luck :)

I could hear a fait beeping in one corner of my kitchen, but if I moved ~3 feet in any direction it disappeared.

Eventually discovered that it was some kind of acoustical beat frequency from the motor noise in the refrigerator reflecting off the back wall. Moved the refrigerator ~1 inch further away from the wall and the sound disappeared (at least from the location I had been able to hear it)

I heard this weird hum in what I would judge as similar frequency band to yours when I stayed at my sisters new house. The thought that I have a weird new ear problem or something really freaked me out at first. And then I realized that I'm only sleeping on a thin mattress directly on the floor and they have a water circulating under floor heating there that just created this hum.

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.

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.

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.

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.

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