• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Low-frequency Hum in my house.

Hayabusa

Addicted to Fun and Learning
Joined
Oct 12, 2019
Messages
786
Likes
518
Location
Abu Dhabi
Those usually whine. Plus we can't hear it outside.
Pumps could put vibrations into the ground which propagate to the house and cause audible sound.
 
OP
C

CBM

Active Member
Joined
Aug 7, 2020
Messages
109
Likes
49
Can you feel vibration when you put your hand on a wall or floor?
I should have thought of this before but after your post I put my ear to the wall (any wall) and I heard it. Then I tried the floor - even stronger. So I turned off the breaker and it was still there. It sounds like a generator under the floor but I've been under there and it's quiet.
Now I'm thinking its caused by water flowing in one of the mains in the street, vibrating the foundation. Whatever it is, it's consistent night and day.
 

JeffS7444

Major Contributor
Forum Donor
Joined
Jul 21, 2019
Messages
2,347
Likes
3,507
Speaking of ducts, at my former workplace, we got to wondering about a small metal box which was situated high up on a wall and which looked like a desktop power supply. Turns out it was a white noise generator designed to mask the rumbling sounds of the HVAC system. It had a couple of controls which controlled pitch and amplitude of the noise.
 

Propheticus

Senior Member
Joined
Nov 18, 2020
Messages
431
Likes
644
Location
Vleuten, Netherlands
That's normal, for whatever reasons.
Isn't that simply because higher frequencies get absorbed more easily than low? If your neighbour plays his music too loud, you'll hear the bass more than anything else. Same idea applies to (far)higher frequencies like; while having a higher (max) bandwidth, 5GHz WiFi has a far shorter range than 2.4GHz. Also see 5G mobile internet and the need for pico and femto cells.
 

RayDunzl

Grand Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
13,198
Likes
16,981
Location
Riverview FL
Isn't that simply because higher frequencies get absorbed more easily than low?

The topic was more attuned to low (below 200Hz) audio frequencies, and their minor frequency variation over time.


5GHz WiFi has a far shorter range than 2.4GHz.

That may or may not be a atmospheric phenomenon. As I remember (or imagine I remember) the higher wifi band is less able to penetrate walls or bend around obstacles.

"The craft (Voyager) normally transmits data to Earth over Deep Space Network Channel 18, using a frequency of either 2.3 GHz or 8.4 GHz, while signals from Earth to Voyager are transmitted at 2.1 GHz."

https://en.wikipedia.org/wiki/Voyager_1#Communication_system

Those signal bands probably wouldn't have been chosen if our atmosphere were opaque to them.
 
Last edited:

Propheticus

Senior Member
Joined
Nov 18, 2020
Messages
431
Likes
644
Location
Vleuten, Netherlands
I know it was about audio. But also there higher frequencies get absorbed/blocked more by things like walls and windows than low ones. This explains why your (in house) environment noise measurement shows more low noise than high.

The same happens in far higher frequencies. Bricks, concrete, etc block high freq bands more than low ones. Obviously there's no walls between the voyager and communication dishes atop a mountain top.
 

mSpot

Senior Member
Joined
Nov 15, 2018
Messages
404
Likes
519
Now I'm thinking its caused by water flowing in one of the mains in the street, vibrating the foundation. Whatever it is, it's consistent night and day.
If you confirm that the vibration is transmitted from outside plumbing, there are plumbing vibration decouplers that may help (basically a section of flexible pipe that won't transmit vibration). However, it would involve hiring a plumber and digging up outside the house.
 

Speedskater

Major Contributor
Joined
Mar 5, 2016
Messages
1,610
Likes
1,333
Location
Cleveland, Ohio USA
I would think that in most residential neighborhoods there are long periods during the day/night when no water is flowing. Any near-by water storage towers? How about sanitation plants? Any manufacturing? Any big apartments or schools?
 
OP
C

CBM

Active Member
Joined
Aug 7, 2020
Messages
109
Likes
49
If you confirm that the vibration is transmitted from outside plumbing, there are plumbing vibration decouplers that may help (basically a section of flexible pipe that won't transmit vibration). However, it would involve hiring a plumber and digging up outside the house.
I'm thinking that the water in the mains may be vibrating the ground and the foundation of the house. I can't think of anything else that would only make a sound in the house but not outside and that would be noisy when the power is off.
 

Don Hills

Addicted to Fun and Learning
Joined
Mar 1, 2016
Messages
708
Likes
464
Location
Wellington, New Zealand
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.

Some modern smartphones appear to have DSP based noise cancellation. I was video chatting with my daughter, and she turned on a vacuum cleaner. It was loud for a couple of seconds, then faded away to silence. I could still hear her speaking, although it was somewhat choppy and distorted. I experimented and found my phone does the same thing for cell phone calls and voice / video chat, but not when I use an app for recording audio. The same thing could be happening when you record video.
 
OP
C

CBM

Active Member
Joined
Aug 7, 2020
Messages
109
Likes
49
I would think that in most residential neighborhoods there are long periods during the day/night when no water is flowing. Any near-by water storage towers? How about sanitation plants? Any manufacturing? Any big apartments or schools?
No. But its a 100+ year old neighborhood. The mains have probably been replaced over time but I'm sure they are old.
 

Soniclife

Major Contributor
Forum Donor
Joined
Apr 13, 2017
Messages
4,499
Likes
5,417
Location
UK
Maybe. But I think you would hear that outside.
Not if it's masked by a higher noise floor, and your earlier measurement shows there is a higher noise floor outside, as normal.
 

dasdoing

Major Contributor
Joined
May 20, 2020
Messages
4,209
Likes
2,673
Location
Salvador-Bahia-Brasil
in order to get better graphs we should
a) look at the time domain (waterfall plot)
b) not use the record function in rew but record an audio file of 10s or so and then import it as audio data
then set the waterfall time window to max it out.

why? now we can see what noises are just noises and if there is a continuous hum it shows up as a straight peak over time.
in my case I detect no humming here (ignore SPL, not calibrated)

fdfd.jpg


the "peakier" region between 35 and 55 is the nearby ocean (I dont hear it at recording time; but I can identify it on the recording)
 

mSpot

Senior Member
Joined
Nov 15, 2018
Messages
404
Likes
519
I should have thought of this before but after your post I put my ear to the wall (any wall) and I heard it. Then I tried the floor - even stronger. So I turned off the breaker and it was still there. It sounds like a generator under the floor but I've been under there and it's quiet.
Now I'm thinking its caused by water flowing in one of the mains in the street, vibrating the foundation. Whatever it is, it's consistent night and day.
Can you detect the same vibration in the sidewalk or street? Something to determine is whether the ground around the house is vibrating or if it's transmitted into the house through something specific like plumbing. What type of foundation is it — concrete slab, concrete footings with crawlspace, full basement?
 
OP
C

CBM

Active Member
Joined
Aug 7, 2020
Messages
109
Likes
49
in order to get better graphs we should
a) look at the time domain (waterfall plot)
b) not use the record function in rew but record an audio file of 10s or so and then import it as audio data
then set the waterfall time window to max it out.

why? now we can see what noises are just noises and if there is a continuous hum it shows up as a straight peak over time.
in my case I detect no humming here (ignore SPL, not calibrated)

View attachment 117633

the "peakier" region between 35 and 55 is the nearby ocean (I dont hear it at recording time; but I can identify it on the recording)
I have tried 3 different methods to record the hum without success. I tried my phone with a Dayton IMM-6 mic and the android video recorder, my phone and mic with a 3rd party app, and my windows 10 computer with a UMIK-1 mic and the microsoft voice recorder app. All I got was normal ,room sounds. I think the apps I used don't record low enough to pick up this rumble. Do you have a suggestion on how to record it?
 

Juhazi

Major Contributor
Joined
Sep 15, 2018
Messages
1,717
Likes
2,897
Location
Finland
Freeware RoomEQWizard is very good. Use it's RTA recording/analysis function like seen in many posts here.

Help section is recommended reading.... there are many option for recording. REW is typically used to analyze room modes taht happen at very low frequencies, so default settings are a good start. UMIK-1 works very well with REW.
 
Last edited:
Top Bottom