Help! Deep bass repetitive noise in house - but from where and what is it?

DawlishDilbert

For the past few months I've been hearing a strange noise in the house. Usually between 16:00 and 09:00 but worse at night (when no other noises). Some quiet periods in that time but it does seem to peak at around 04:00.

There are some different variations but the main two are
1. two notes alternating in a very low key, at low to medium volume. Imagine 2 strings being gently plucked on a bass guitar. Pattern can be A B A B or A B A B B A A B AA B. or just A B A B A. One note then a gap of a couple of seconds, then the next. Same 2 notes.
2. Second is similar low (Bass) note muffled knocking without the regular repetition.

There's NO scratching, squealing, or sense of movement. It's also impossible to identify where it's coming from (possibly a feature of the low pitch of the noise) noise can be heard throughout the house (3 bed detached 1970s).

We've had pest control in, and no takers for squirrel/rat or mouse bait & traps in the attic. Also checked for access. In fact I've. been in the attic and heard the noise when there. 
I've tried switching water off at stop-!!!!!! and also switching boiler completely off. Still hear it overnight.

I'm thinking next of a different pest controller (perhaps to infrared look at cavity walls) and also checking with plumbers (courtesy B.Gas contract) for ideas but has anyone else experienced anything like this please?

Thanks in advance.

theoretica

Another thing to try is all electrics off at the mains.  I too have a mystery humm, but think it comes from next property over.

Rosa_Damascena

theoretica said:

Another thing to try is all electrics off at the mains.  I too have a mystery humm, but think it comes from next property over.

When does a mystery hum turn into an electrical fault? I would like to hear the answer "never" but that might be a touch idealistic.

OP - does the noise have any relationship with your boiler / HW tank? Eg if you leave it on all day so it can maintain temperature?

kdotdotdotdot

You're not in Bristol, by any chance?  https://www.bbc.co.uk/news/magazine-35344544  It does sound like you're describing 'the Bristol hum'.

DawlishDilbert

No, not in Bristol! and it isn't a hum as such, just these muffled knocking/bass guitar string-pluck! I've turned the C/H system (gas) off overnight and still heard it. Same with stop-!!!!!! - though I didn't drain the water tank in the attic down. I'll certainly try the power off at the mains as that should stop it dead if it is electrical. 
We have a valve thing on the toilet vent (ie not through the roof, but some sort of valve on the pipe hidden in a unit in the bathroom - called a drunge valve or something!!!). Wondered if that but the noise is from everywhere - not just the area of this valve.

DawlishDilbert

DawlishDilbert said:

No, not in Bristol! and it isn't a hum as such, just these muffled knocking/bass guitar string-pluck! I've turned the C/H system (gas) off overnight and still heard it. Same with stop-!!!!!! - though I didn't drain the water tank in the attic down. I'll certainly try the power off at the mains as that should stop it dead if it is electrical. 
We have a valve thing on the toilet vent (ie not through the roof, but some sort of valve on the pipe hidden in a unit in the bathroom - called a drunge valve or something!!!). Wondered if that but the noise is from everywhere - not just the area of this valve.

Of course for 'stop-!!!!!!' read 'stop-c o c k' or does it bowdlerise that too?

Rosa_Damascena

DawlishDilbert said:

DawlishDilbert said:

No, not in Bristol! and it isn't a hum as such, just these muffled knocking/bass guitar string-pluck! I've turned the C/H system (gas) off overnight and still heard it. Same with stop-!!!!!! - though I didn't drain the water tank in the attic down. I'll certainly try the power off at the mains as that should stop it dead if it is electrical. 
We have a valve thing on the toilet vent (ie not through the roof, but some sort of valve on the pipe hidden in a unit in the bathroom - called a drunge valve or something!!!). Wondered if that but the noise is from everywhere - not just the area of this valve.

Of course for 'stop-!!!!!!' read 'stop-c o c k' or does it bowdlerise that too?

Nope, but it doesn't like the Lincolnshire town of Scu*thorpe nor what you could do with a fork either.

DawlishDilbert

Not power-related as I could hear it during a recent power-cut. During late Aug/early Sept it was less persistent, but mid Sept it's back - much quieter, and only from around 03:00 - 07:00 in the morning. Still can't pinpoint location. 

Who do I even get to help? we've had pest-controller in. Could it be something in the building itself? i.e. it's about to fall down or roof get blown off? Building surveyor? engineer of some sort. 

Homer_home

Can you record it so we can hear it?

Can anybody else hear it?

What's the weather doing when you can hear it, is it windy?

Davesnave

Rosa_Damascena said:

DawlishDilbert said:

DawlishDilbert said:

No, not in Bristol! and it isn't a hum as such, just these muffled knocking/bass guitar string-pluck! I've turned the C/H system (gas) off overnight and still heard it. Same with stop-!!!!!! - though I didn't drain the water tank in the attic down. I'll certainly try the power off at the mains as that should stop it dead if it is electrical. 
We have a valve thing on the toilet vent (ie not through the roof, but some sort of valve on the pipe hidden in a unit in the bathroom - called a drunge valve or something!!!). Wondered if that but the noise is from everywhere - not just the area of this valve.

Of course for 'stop-!!!!!!' read 'stop-c o c k' or does it bowdlerise that too?

Nope, but it doesn't like the Lincolnshire town of Scu*thorpe nor what you could do with a fork either.

Actually, residents of Scunthorpe can now say so on this version of the Forum. On the old one, 'stopcock' was possible, but I'm not sure about this one....let's see.

Seems to work for me.

Skint_yet_Again

Have you asked the neighbours if they can hear it too ? My fridge freezer makes lots of noise but as you said it continued in a power cut it’s obviously not that 😆