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Question DetailsAsked on 3/20/2017



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5 Answers


Here are some similar questions with responses listing a fair number of common causes which might help -

You can do this sort of tracking down by ear (pressing ear against the wall or pipe or floor) but getting a $10-15 metal head (work much better than plastic head ones for this) stethoscope from local pharmacy department works better and avoids having to get into really awkward positions on floor or against wall. Start at electrical meter both outside and on the inside wall behind it (because when you turned the power off you only turned off the power on the house side of the meter - not the meter itself, which would still be running). Then check gas and water meter - they can hum at times when in use, especially if a "smart meter".

Also any battery or solar powered devices - including going around to all smoke and CO alarms, any solar chargers or solar powered heater or such, any outdoor powered devices which run off a different main breaker box (like pool area for instance), burglar alarm horn/siren trying to sound but does not have 120V power to it and the backup battery is almost dead, or a battery-backup sump pump running or stalled (stuck but constantly trying to run).

Also put stethoscope on metal gas and water and sewer pipes where they come into the house (or as much outside as you can make direct contact with them) - could be a compressor or pump noise from the utility coming in through the pipes. [On sewer pipes - if they are doing maintenance, especially if doing routine jetting cleaning of the pipes, that sound can carry a mile or more through the pipes - check at your sewer pipe near where it exits house, and if noise is strong there, check at sewer manhole cover in the street.

Check outside noises of things running - especially neighbor vehicles or air conditioners or roof-mounted HVAC units, or maybe a neighbor's shop air compressor or table saw or such being used - it is pretty common for the air vibrations from them to transmit to vibrations in your siding or windows or such. Ditto if a neighbor is having their house painted or reroofed - a paint sprayer, compressor, or pressure washer running can also do this.

Also - with newer direct-vent stoves and furnaces and water heaters - if the vent pipe on a neighbor's house is aimed at yours, can commonly set up a uniform vibration which can range from actually flapping siding (with aluminum or vinyl lap type) to a hum or throbbing resonance in the wall.

Windmills, including even small decorative garden ones or wind-spinners, can also cause this sort of sound at certain wind speeds.

Ditto if you have a steady wind and flapping shingles or a roof turbine ventilator.

And of course if breezy, check for something vibrating in the wind or flapping lightly against the house.

If no joy on any of those, call the non-emergency number (NOT 911) for the police and ask if they have gotten any similar calls about a humming noise - could be some large engine being tested quite a ways away (we hear testing on Air Force aircraft engines being tested about 12 miles away as a humming or dull roar, and when a kid could hear rocket engines being tested over 60 miles away - though those engine test sounds only last a minute or few) - ditto to railroad engines or construction equipment within a mile or two idling (which can go for hours, even continuously in railroad yards or in cold weather where they sometimes keep the equipment running overnight because they fear it will not start next day if they shut it off in subzero weather), could even be microseismic or "earth hum" aka "The Hum" sound (google about that - it is real).

Answered 3 years ago by LCD



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Answered 3 years ago by Member Services


One thing I forgot to mention - toys. We had that happen once, though it was only herd in one end of the house, not all over - a toy in a toybox making a sound (trying to walk while lying on its back as I recall) went for a day or so before the batteries died - did not figure that one out until we heard the same sound some weeks later after the batteries had been replaced, and recognized the sound as being the "mystery sound".

And of course tinnitus - ringing or buzzing in the ears, though going outside in a quiet area or outside sitting in the car and NOT hearing the humming could rule that out.

Answered 3 years ago by LCD


OK - my follow-up with some more sources got chopped off after second paragraph by the Angies List system - reposting it here:

Here is another (new I think) link with a LOT of listed sources of this typeof noise, from several contributors:

One thing I forgot to mention - battery powered toys or electronic entertainment devices, including laptops/tablets/game consoles/pocket electronic games/cell phones. We had that happen once, though it was only heard in one end of the house, not all over - a toy in a toybox making a sound (trying to walk while lying on its back as I recall) went for a day or so before the batteries died - did not figure that one out until we heard the same sound some weeks later after the batteries had been replaced, and recognized the sound as being the "mystery sound".

And of course tinnitus - ringing or buzzing in the ears, though going outside in a quiet area or outside sitting in the car and NOT hearing the humming could rule that out.

One thing on the alarms - many types of alarms, especially full-house alarm systems with horns or sirens, and water alarms / power loss alarms / freezer high temperature alarms / sump pump high water or power loss alarms and those types, give off a buzzing or humming when they go off and are operating only on low battery power, or when only battery operated and either sounding an alarm or giving off a low-battery alarm but the battery is so dead that it only puts out a low hum, buzz, squeek, etc. Though a good walk-around looking for them and listening at each should rule that out pretty quickly.

I did mention roof turbine vents and solar-powered items but I don't think I specifically mentioned roof-mounted solar-powered attic vents, which could hum or whine when running.

I think I did mention insects in the linked responses - wood-chewing insects like post beetles, carpenter ants, and termites make a sound something like a hum when heard at a distance, though close to the nest (stethoscope) is actually a chewing sound from many insects. Many types of worker insects like bees also flap their wings in the hive to cool it when hot, so again a stethoscope job, listening at walls and crawlspace floors - you might have an insect nest in the stud/joist space or attic or crawlspace.

One other thing - rodents - I know from experience with an attic invasion that possums "coo" or "hum" to their babies - though not continuously obviously, and when we had a nest in the crawlspace certainly was not heard throughout the house. But maybe a louder animal like coons do.

Also - if you have a sewage lift pump system because you are down in a hole or the leach field had to be built higher than the septic tank, check if you have a sewer system alarm that is going off (like in a manhole) and maybe passing the sound through the sewer lines to the house - or just a hum from it running if on a different power panel which you did not shut off, or if on a battery backup system.

Ditto if you have a foundation perimeter french drain system with wetwell and sump pump to pump that water out - though in both those cases shutting the power off would have turned them off too (unless they have battery backup), or are powered from a different breaker panel.

One other thing that jogged my mind - I think was mentioned in the referenced links - is slow water running. In addition to very slow pipe leak as I previously mentioned, could be caused by a leak backwards through a checkvalve on the sewer system if you are on a pressure system or have a lift pump or backflow valve because sometimes the sewer lines can back up to your house - so reverse flow through a slight gap in the backflow valve could make a noise like this. Similar sound can occur at times in pressure regulator/backflow preventer on the cold water line if there is a slight flow in the water lines somewhere.

Oh - another thought - an outside hose bib leaking a touch or frozen so wateris escaping through a slight crack - ditto to sprinkler system possible leaking a bit of water through the control box.

And ditto again to water softener leaking a bit of water through the flush valve constantly, even when it is off.

Also - slight water flow from a leaking faucet or toilet outlet or inflow valve. A toilet "running" can make a number of different sounds, including humming, so check with stethoscope at toilet. Can make a noise when outflow is so low that it does not cause a disturbance in the toilet bowl water- though could eventually (depending on flowrate and how often the toilet is used) eventually cause "ghost flushes" where the inflow valve runs for a very short time to refill the slow drawdown from the leakage out of the tank. Can also be from leaking/sticking/gunked up toilet inflow valve - causing a constant very small inflow to the tank, which would usually lead to some water dripping out of the bowl refill tube (the small tube from inlet valve into the top of the overflow tube), or slow filling of the tank by the inlet valve, resulting in very minor (possibly more a "wicking" than a flow) overflow into the overflow tube, which leads to the bowl.

Not a continuous sound, but furnace exhaust fans on high-efficiency direct-vent furnaces and boilers and water heaters sometimes run for some minutes after it stops firing, some water heaters have heat pumps on top, compressors (A/C and reefer and any separate deep freeze) commonly make a humming or wheezing or whistling sound as the pressure drops off right after they shut off - but again only for a minute or so. And of course, if the power were shut off to them such a sound would diminish within a minute or two.

One other water running possibility - makeup water refilling boiler (inlet valve at pressure regulating tank operating to replace vented air in boiler) though again only for a few seconds at a time. Ditto to venting of air from a hot water/steam heating system. Continuous sound could occur if there is a leak in a radiator or pipe in a steam or hot water (hydronic) heating system, including in-floor loop heating - though eventually one would expect a leak to show up somewhere (though might be in crawlspace or wall or other out-of-the-way space).

Another possibility - leaking or slightly operating (rightly or wrongly) overtemp/ overpressure valve on water heater or boiler - slightly leaking water out the overflow pipe, which if run into a drain might not make for a visible wet spot.

Compressor leaking - though if heard through house an A/C or reefer/freezer compressor would be expected to run out of refrigerant in hours or a day or so if leaking enough to be heard like that. But a workshop compressor left turned on could be bleeding air at a hose fitting - though would be expected to kick back on periodically to recharge the tank as the pressure drops.

Ditto to a pressure tank leaking water or air - on well pump, or large surge or pressure relief tank for water heater/boiler (some of the old ones were water-heater sized ones put in the overhead floor joists). Could make noise as long as there is pressure in the system.

Ditto to leaking foot valve if you have a well pump - allowing a slight leak back into the well under pressure - could make a whine or humming sound which would carry through the pipes and water column throughout the system.

Guess I have run out of thoughts - other than maybe the Three Chipmunks have moved in and are warming up their humming to practice for a new song.

Good Luck finding it - and I would appreciate it if you could use the Answer This Question yellow button right below your question to respond back with what it turned out to be, for future info on questions like this - and out of simple curiousity.

Answered 3 years ago by LCD


Ahh - found the other few links I was looking for, with previously posted answers on possible causes for the noise - the responses to your question now contain pretty much everything I have found that has been posted on AL about mystery noises in a house.

One other last thought I ran into once or twice - either a current hum or a wind-induced vibration in your weatherhead (where the overhead wires go into the conduit at the house before they go down to the meter) - can hum or make a noise there from the A/C hum in the wires, or from the wind moving/blowing over the suspended cables, which then gets amplified into an audible sound in the conduit (which acts like a resonating sounding tube, like in a woodwind musical instrument). Remember, when you turned the power off, you only turned it off from that breaker or disconnect switch into the house - power was still "live" on the incoming side of that, including the transformer, weatherhead, meter base, and wiring from meter to the point where you turned it off.

Answered 3 years ago by LCD

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