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Question DetailsAsked on 5/1/2016

How do I find out the cause of a low frequency hum in my house?

The noise is coming from every room of the house, most all the time now. I do not hear it anywhere else and at times have to wear ear plugs to alleviate me getting dizzy at times. I have spent 400 dollars on heating and air and electricians, with them putting a surge protector on my fuse box. The power company and the water company have not taken responsibility. I just thought today about calling the gas company. Since I had my furnace and water heater checked out by the heating and air comp[any I thought all would be fine, but probably should have them come out. I live in a townhouse and no one else is saying they hear it. Although sometimes I hear it in my detached garage. I stay away from my townhouse as much as possible as the noise is not allowing me to get any relief and sometimes is louder at night. I wear ear plugs all night long. This noise also makes me feel like a surge of electricity is going through me when it is very loud, but very low frequency. Please help.

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2 Answers


Find a good audio technician. Maybe someone who installs and repairs home entertainment systems and audio / visual equipment. I'm sure they see low frequency hum all the time. In audio equipment, 60 cycle hum is caused by faulty power filter capacitors. However, your house is not a piece of audio equipment, and as such, does not have capcitors or speakers in the wiring.

Answered 4 years ago by Kestrel Electric


You can find some prior similar questions with numerous possible causes itemized in the responses if you put the word - hum - into the Ask box - it will pop up several related questions, and each of them has others listed below it. Some of these I will repeat below, but not as exhaustive as a couple of the lists of possible sources I have put in prior responses.

Assuming this occurs ONLY at your place - so not tinninitus or such (which you should hear at other places where it is not very noisy), I would track it down like this (see other links for more detail) - and unless you are hearing it clearly wait till quiet times outside/neighbors so you can clearly hear it.

00) some time when you hear it well, get in your car and drive a block or so and see if you still hear it - if so, most likely tinninitus and you are just noticing it in your house because it is quieter there. Ditto to being noisier at night - probably just seems that way because it is quieter then - plus at night your senses tend to getmore attuned as a heriditary relict defence mechanism, to hear critters creeping up on a sleeper.

0) walk around OUTSIDE of your place and see if you can hear it - if so, trace down where it is loudest - might not be coming from your place. Might be a vbentilation unit or air conditioner or such on adjacent building. If not, then probably from inside of building.

1) ask neighbors if they hear it at their place and if they have tracked down the cause or where it is loudest from their unit - though I see you said they are not mentioning hearing it - but does that mean they just have not mentioned it to you, or that your have specifically asked them ?

2) walk around all rooms (including at basement/crawlspace) in succession to see if louder in one than others - and maybe having a friend do so also for a second opinion. Basically, if not louder in one room than others, likely coming from a connected space in the house (attic or basement/crawlspace) or from outdoors, though if from outdoors usually would be louder at one side of house than the opposite. Might help to make yourself a rolled-up cone "ear horn" to more clearly isolate which way the sound is loudest. Or hold a small-mouthed plastic or metal container like a 2L soda bottle to your ear to amplify sound from that side.

3) start with major utilities and appliances - listen at electric meter, gas meter, water meter, furnace/boiler, air conditioner, water heater, water softener or purifier (including filtration or reverse osmosis point-of-use units), sprinkler or irrigation system, well pump (including any treatment tank at that location), power transformer (or as close as you can get to it on ground if pole mounted), doorbell transformer (commonly near front door under stairs or similar hidden place - usually hidden up in floor joists. Might also be a fan stalled or running continuously, a circulating pump making noise, even an appliance like a water softener out-of-salt alarm going off, or a hardwired water or freezer loss of power or overheat alarm that has mostly died so it hums instead of making an alarm sound. Also listen at reefer and deep freeze (if any), and any dispensing units like coffee maker, water chiller, soft drink maker, etc which are always on standby or on.

4) go around each room one at a time, turning off all light switches and unplugging anything operating in that room to see if shutting one item off stops it. Just turning the item off might not work if an always-on item like a TV or computer where you push a button on the device to turn it on, because those type items almost always have an internal transformer live, which can hum. Also, plug strips and surge protectors can make funny noises at times when going bad. Obviously, stereo equipment, computer auxiliary speakers, TV's, intercom systems and the like type of audio equipment is an obvious first thing to check. Ditto to alarm systems which sometimes make a low pitched hum when their backup battery is dying and the alarm is going off - the alarm horn may just buzz or hum rather than sound as a horn or alarm siren. Ditto to outdoor security lights - especially halogens - when they start going bad may be trying to constantly restart, or the starting circuit may be going out and humming. Ditto to flousescents that are always on. Stuck doorbell switch can also make the transformer or chimes/doorbell hum.

5) look for any sort of fan or pump that might be making the noise - an attic ventilation fan (gable or through-roof), bathroom or kitchen fan left on and stalling out because the blade is caught on lint or such, basement ventilation fan, instant-on hot water circulating pump getting noisy as bearings or seals start going out

6) check also for indoor or outdoor (wetwell) sump pump which might be stuck in on position (or be pumping continuously). Ditto to sewage lift pump if you have one either in-house or at the septic tank to lift the dewage to a higher-elevation leach field.

7) check pool/hot tub pumps, sauna heater/steam generator, etc

8) if all those ideas fail, try turning off the circuit breakers on at a time till you hit one that shuts off the noise, then start tracing items on that circuit.

9) if going around to all those does not tie it down, then get a $10-15 METAL head (much better than plastic head ones which are only about $5 cheaper) and start listening systematically all around the house - first at pipes (water and sewer) then at walls and floors and such. Will likely hear it everywhere to some exten t if as loud asd you say but not tough to tie down where in a room the sound is strongest, then move in that direction into next adjacent (or above or below as applicable) room to track down the source. Don't forget to listen at party walls because could be coming from a neighbor's unit. [Note - with a stethoscope you will hear water running in the other units, possibly fans in their units, etc - so you will have to discriminate between normal noises from their units and your sound.]

10) remote but does happen - if having electrician check if the power and metal piping system is properly bonded and grounded - sometimes a bad or non-existent ground can cause a low-frequency hum in the elecrtrical system. Ditto to metal roofing or siding picking up and resonating with static hum if near a major powerline.

11) if can hear well at pipes, turn off main water supply valve (outdoor shutoff if you can) and then listen at pipes to see if goes away - if so, then a pump or slightly leaking valve humming. When off, if on public water, see if the meter is moving - if water shutoff valve is off at house but meter is moving, could be a water pipe leak.

12) rarely but can happen - metal siding or soffit or trim piece resonating with the pulses of air pressure from yours or neighbor's air conditioner or fan exhaust.

13) see if you can tie the sound (if intermittent) to a specific linking possible source - like water heater firing because hot water has just been used, furnace or boiler running, etc.

14) neighbor's bug zapper

You did not say if the HVAC contractor or water or power guys heard the sound or not. Or what they found, if anything. The surge protector was a waste - he should have been able to determine if you were seeing surges before putting that in, and that would VERY rarely be the cause unless on private power. More commonly noise from electric systems like this is stray superimposed waveforms but not surges that a surge protector would stop (which generally are set to only stop voltages over say 400 volts on 110/120V line) - if you are getting electrical "noise" from somewhere then a waveform filter and power stabilization unit would be necessary - but if that is the case cheaper to find the source and have THEM stop it.

If unable to check out the possibilities yourself due to age or health or such, then my choice would be either a Civil Engineer (who is trained in logic and scientific method of investigation) who deals in residential construction issues, or a Home Inspector (latter generally cheaper). Granted not normal thing for a home inspector to check out, but he is familiar with houses and household utilities and various types of appliances and such, and is used to climbing through the house and into attics to check things out, so a logical choice as long as he has good hearing.

Last resort would be an Building Environmental Health engineering firm - they normally look for environmental health issues like fumes and respiratory issues (and normally in commerical buildings) but a decent sized firm should be able to easily come up with (inhouse or rental) a precision ambient sound detector system to track down the sound source.

BTW - let us know the source, to settle our curiousity. Use the Answer This Question yellow button right below your Question to respond back, as if you were answering your own question - that will keep it all in the same "thread" or question.

Answered 4 years ago by LCD

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