A thread with this problem has been closed. See https://www.askmehelpdesk.com/plumbing/mysterious-humming-noise-house-55517-11.html In case the problem is continuing with others, I want to report our experience.

We live in central London, on the fifth floor of a modern reinforced concrete frame apartment building. There is a storey above ours at the rear of our flat, and a roof terrace above at the front (not ours). The block is all electric. There is a cold water tank in the basement, which pumps water to the flats. Water is heated within each flat by a PulsaCoil. There are 2 air conditioning units in the terrace above us. These were overhauled last summer and apparently a hole drilled through the outside wall for connect. Of course individual flats also have extractors to bathrooms and kitchens. This is all the potentially relevant information I can think of.

We lived in the flat for 4-5 months without hearing any hum. Then it started, very low vibrating sound, on and off, on and off. It is hard to find a regular pattern. It is often heard in the late evening and sometimes wakes me up at night. When it is bad, you can feel the floor vibrating. It actually hurts my ear when it is bad.

It is not tinnitus. My partner hears it as well, as did a visitor without it being pointed out to him. The hum went on and off last summer, then stopped. I heard it one day in November, then didn't hear it. It resumed recently and is driving me crazy.

The porter says that he asked other flats, but no one else in the building hears it. It is not coming from our flat. It is loudest by the boxing in of a soil stack that is in our living room (bathroom in flat below), but the sound also transmits, curiously to a bedroom on the opposite side of our flat.

Any suggestions? Help ! Thanks.

About my post, I should have said, it can go on and off for hours on end, sometimes for the better part of the day and/or through the night, so I can't think it is merely a noisy bathroom extractor.

Don't think this is your problem but I'm just researching this.. and came across your... that fact your floor is vibrating... makes me feel its not the same...

Anyway this is how I got here... their a few more post on this site... saying the noise sounds like a fog horn going off I imagine that quite loud...

I repost mine but mine sounded like a cat purring in my wall its as follows: go listen to the YouTube sound

Hey was just researching this as I have this, noticed this , mine it sounds like their a cat stuck in my wall and it purrs really low pitched...

Here's how I came across this page
https://www.google.co.nz/?gfe_rd=cr&...ke+its+purring



Here's the sound

https://www.youtube.com/watch?v=IfdoigG75dQ

Of course this is way louder on a phone recording

I also had a cricket stuck down my shower hole.. you can imagine how loud they are... amped by the sound bouncing in the bathroom walls, think there might be a hole under the house that insects can get in... under the shower.

So mines next to my pillow... in the bedroom

And my bathrooms has its own different problems.

Dumb noises aye... and only at night.

Don't know if you're the same problem... but some info!! My research has come to bee nests. Think that's my answer

A hive of bees gives off a low buzzing noise. It's all the bees in the hive flapping their wings to regulate the temperature. Depending on how thick the wall is between the hive and the inside of your house, it could be very faint.

Of course, the bigger the hive gets, the louder it gets, and the more expensive it will be to finally fix. Thousands of bees make a lot of honey, and having your wall full of honey isn't as great as it sounds at first.