Low-frequency Hum in my house.

[CBM]

I have no suggestions for the source of the sound, just a suggestion for anyone who might find themselves with a requirement for using a smartphone for recording. Smartphone microphones aren't optimised for full-range recording. I use a cheap lapel microphone with a smartphone plug - it has the same plug as a smartphone handsfree earplug / microphone set. They are also available with USB-C plugs if you have a recent phone with only USB-C. It has wider frequency range, more sensitivity and lower hiss than the built-in microphone.

I used a Dayton MM-6 mic with my phone. It got similar graphs to the minidsp umik-1 & REW but when I tried a video I just got higher frequencies. It must be the video app doesn't have low range.

 

[JeffS7444]

My own room noise, refrigerator not running. 85 Hz peak just started and seems to correspond to a neighbor's subwoofer which is faintly but clearly audible, as is the sound from passing cars, and the fan in my PC.

 

[CBM]

Do you have 12 foot ceilings thru out the house. or is the main floor about 12.5 feet over a basement? The 44 hz corresponds to something resonating at 12.5 feet spacing or a 25 ft wave.

I have a long listening room and the longest dimension is not quite 34 ft. So it has a resonance of 17 hz. You can see in noise peaks of 17 hz, 34 hz and 51 hz. I don't have any particular source at any of those frequencies, but I take it low frequency pinkish noise excites those resonances. Those peaks grow higher when a train rumbles down a nearby track because it injects more random noise into the structure for it to resonate.

Another possibility is AC ductwork running down the center of your house and each vent branches off going 12 feet or so to the vent and all those ducts the same length resonate. If so it should be worse with AC running, but will still resonate at low levels with the AC off.

The ceilings are 9 feet but I never thought about the ducts with the AC off. I'll have to think about that. They do go in every room of the house. Thank you.

 

[CBM]

I still think you have a motor running in the house you don’t know about. Do you have a sump pump in your basement? A condensate pump in your air handler? A radon mitigation fan? An attic or laundry room ventilation fan? A leaky Sleep Number mattress? A muffin fan with a bad bearing on the NAS stuck in the office cabinet? All of those have made low-level mystery roars for me at one time or another. If it sits on a hard floor or is screwed to a wall, it can resonate the whole structure.

This can get weird. The ceiling fan in our den was an old cheapie installed by the previous owner (and we moved here 19 years ago), and the rubber damper ring rotted and the fan-blade assembly dropped to the floor. I put it out on the porch while I looked for the part (which I never found). Several weeks later, my wife complained of a low-level noise. Took an hour to localize it. When the blade assembly fell, it pulled the pull switch and the fan motor was happily spinning away, turning only its narrow mounting hub, too quiet to be obvious but not silent.

Rick “who has heard several of these through the pillow at night, at least before CPAP” Denney

Well, I cut the breaker earlier and the noise was still there and it still measured so the source would have to be mechanical.

 

[CBM]

I would have expected the outside and inside to have similar frequency peaks.
Me too. It sounds like it's being generated inside the house. But when I opened the main breaker, it was still here and I got the same peaks on my phone app.



Outside noise does that as different sources find a path to you as the atmospherics change.

At Audio Buddy's house, who lives 1/2 mile from a busy expressway, on an otherwise quiet evening, while standing on the porch, sometimes every vehicle passing by is heard, and other times we hear none at all, depending on the microclimate of the moment.

View attachment 117335

https://rosap.ntl.bts.gov/view/dot/40318/dot_40318_DS1.pdf

 

[Boris Badinov]

Nope. The hum sound is the same whether living in a busy city in an apartment or out in the countryside in a completely different part of the country. I heard it in the UK and also in the US. The best description is a far distant diesel generator attached to bedrock. My partner doesn't hear it and neither do my boys. It's so obvious to me I questioned my own ears/sanity.

It cannot be explained (I tried everything for 30 years) and once you've heard it, you can always hear it. Sometimes it bothers me, but the days of it driving me mad are long gone.



I had the actual drop to the house disconnected and the hum was still there.

I had a friend who was a home builder. He was was ready to pour the foundation for a 2 story house when they discovered that a 5-6 ft portion of the footer would rest on solid rock. The foundation height had to be raised & partially filled with sand and compacted to act as a buffer between the rock and the concrete footer to avoid ground vibration and noise.

 

[rdenney]

Quickie FFT in my room. Internal iPhone mic which is calibrated but still low resolution at low frequencies. I have a hump at 50 Hz and another one at 150 Hz. I suspect it’s the thermostatically controlled cooling fan I have sitting on my amps, which are all warmed up at the moment.

Nope, here it is with no fan. The 50 Hz peak is still there.

But the fan knocked a noticeable dB (SPL, C-weighted full band) off the broadband noise level.

I do not hear the 50-Hz peak.

Rick “no 22.5-foot parallel walls that I see, but modes are weird” Denney

 

[Blumlein 88]

Quickie FFT in my room. Internal iPhone mic which is calibrated but still low resolution at low frequencies. I have a hump at 50 Hz and another one at 150 Hz. I suspect it’s the thermostatically controlled cooling fan I have sitting on my amps, which are all warmed up at the moment.

View attachment 117355

Nope, here it is with no fan. The 50 Hz peak is still there.

View attachment 117357

But the fan knocked a noticeable dB (SPL, C-weighted full band) off the broadband noise level.

I do not hear the 50-Hz peak.

Rick “no 22.5-foot parallel walls that I see, but modes are weird” Denney

They'd be 11.25 ft spacing for 51 hz.

 

[rdenney]

Sure enough. Still don’t know where there’s 11.25 feet, though. All those distances are between non-parallel surfaces.

Rick “brass instruments are closed-end pipes and double the resonant frequency” Denney

 

[Pdxwayne]

Any neighbors near by with swimming pool?

My friend used to live next to a neighbor who installed a pool and the low vibrations of pumps caused them many sleepless nights.

 

[mSpot]

Can you feel vibration when you put your hand on a wall or floor?

 

[Wombat]

Those usually whine. Plus we can't hear it outside.

You may not hear ground vibration transmission but your house my be physically tuned to it.

 

[Wombat]

Any neighbors near by with swimming pool?

My friend used to live next to a neighbor who installed a pool and the low vibrations of pumps caused them many sleepless nights.

Currently happening to my sister and her family. They know where the source is but the neighbour is not co-operative. Local authorities are very slow to get involved.

 

[Juhazi]

In our capital city Helsinki there are now many huge heat pumps installed in service tunnels that cover part of the city. Some apartment houses are vibrating like hell so that people can't sleep!

I live in a house built in 2006. Lower floor is partly underground and made of concrete, upper floor is wooden frame. Air vent hum and refridgerators are the worst intrinsic noises that I can hear. Heat pump's compressor noise is low and intermittent, worst when outoor unit is defreezing. My tinnitus overruns most high freq noises. 50Hz mains here. I guess wife watching TV isn't counted as noise? Fortunately no young kids around any more!

 

[restorer-john]

Currently happening to my sister and her family. They know where the source is but the neighbour is not co-operative. Local authorities are very slow to get involved.

When our neighbours moved in, I taught him how to look after a pool, 'helped' him when the water level dropped and the pump sucked air, vacuumed all the gum leaves and balanced all the chemicals when they went on holidays and I looked after the house. Repaired his cell, cleaned it with HCl etc. Showed him how to backwash, clean pump baskets etc. He doesn't really care about the pool and the kids don't use it. Pity.

Even gave him a perfectly good spare pump and salt water chlorinator I got from a friend who demolished his old house- one that had a timer that worked. The only time I have to mention the pump motor now is if there has been an extended power cut and the on/off timer gets out of sync with the actual time.

We have a man across the road who run a large pool cleaning company and yet the neighbours don't even talk to him, letalone get hm to look after their pool. Makes no sense, he's a cool guy.

 

[mSpot]

It could be gigantic sandworms burrowing underground.

 

[GeekyBastard]

I have the same issue in my home, and it's driving me crazy, it's been humming for at least half a year already, the hum peaked at 40Hz,for about 55dB and up, the frequency seems to be below 100Hz as well, I've tried power off everything in my home, nothing worked so far... The hum makes me nauseate badly, feels like my whole body's shaking with the hum.

I've been using brown noise to help me sleep, apparently brown noise can make your ears ignore the humming sound, a little escape in this vibrating hell so far.

 

[axbarker]

Is there an electrical substation close to your house in the street - possible ground based vibrations resonating with the house structure?

 

[Soniclife]

Inside View attachment 117317
OutsideView attachment 117318

What do they look like without smoothing? It's not clear from that if the tones are still there outside but now lost in the noise floor.

A pub near us sometimes has outside events, we are far enough away that it's hard to hear, but oddly it can be more audible inside with the windows closed than with the window open, the extra other outside background noise masks it. It's the low frequency thump that's audible inside, opening a bedroom window has been enough to drown it out.

 

[Patrick1958]

This is a little off topic for an audio forum but I'm hoping someone with a microphone can measure the noise in their house and tell me if this chart is normal.

We live in a 89 year old house and for the last few months we have heard a low-frequency rumble sound all the time. Even with everything in the house turned off. It's the same everywhere in the house but we don't hear it outside or under the floor (pier and beam) or in the attic. It's constant and unchanging so I thought I would measure it with my microphone and REW. There seems to be a higher level of noise below 100 Hz on REW.View attachment 117246. I would like to know if this unusual or is it common in a house? It's driving us crazy and causing loss of sleep. The trace is with 1/6 smoothing.

Maybe some bass traps tuned to 25 and 50 Hz could bring some relief.