Microphone picking up "no-existent" sounds

Apologies if this is not a Audacity problem.
I’ve upgraded to Audacity 2.3.2 and the only other change to my computer are Firefox upgrades.
Audacity has always worked flawlessly.
After loading Audacity I then clicked on Microphone monitoring which shows there are sounds present, up to the -18 mark.
Recording this output produces just “mains hum”
Trying to record from the net (YouTube or F1 news) produces the same “mains hum”
All sound output from the net or CD’s produces normal results.
I’ve tried an earlier version of Audacity with the same results.

Any ideas before I try another audio software to see if the results are the same.

That doesn’t ring bells.

Audacity doesn’t “do anything” to the sound on recording. No filters or effects. If you turn your speakers up on a Youtube show, do they hum?

Post a little bit of it on the forum. Sometimes the sound signature tells us stuff.



" If you turn your speakers up on a Youtube show, do they hum?" No everything works as it should and has been for years
“Mains Hum” file attached.

Scroll down from a forum text window > Attachments > Add Files.


I’ve added the file but I’m not sure if I have to post a number of replies before they show.

A forum elf is going to read your submission before it becomes visible.

That’s just a festival of contradictions. That’s open shield hum featuring US power tones at 120, 180 and 240. You posted complaining about “Mains Hum” which typically happens in the UK which has very different power tones.

Describe your computer. It’s nearly 100% broken soundcard, microphone, preamp or other sound system. Computer systems don’t have contact with the power lines, so I really have a rough time believing it’s directly related to the upgrade.

Trying to record from the net

I think that’s the phrase that pays. Recording from the net requires special setup and sometimes software. That can totally get messed up if you change your system.

One of the variations of this setup allows you to record “everything playing on the computer” including that broken gaming microphone you forgot you had connected.

You can try “start from zero.”

Shutdown. Not Restart, but actual Shutdown. While it’s down, disconnect everything. Network, drives, sound, preamps, second external monitor, everything. Start.

Did you have any problems when it came back up? Does the machine have a built-in microphone? Does it work?


I am in the UK and it just sounded like “Mains Hum”.

Processor - Intel(R) Core™ i5-4690K CPU @ 3.50GHz.
Sound Blaster Audigy FX sound card.

All sound output from the net (Youtube, BBC iPlayer, other sound sites) or CD’s produces normal results so it seem to be working.
There is no physical microphone.
The last time it worked ok was in May and as I’ve said only upgrades to Audacity 2.3.2 and Firefox have been added.

It will take a while to test the “start from zero” strategy, so I’ll come back.

It will take a while to test the “start from zero” strategy

I don’t know where else to go with that. How do you get US mains hum in the UK?


as I’ve said only upgrades

Nobody wrote anywhere you can’t have more than one problem.


Good question.