Buzzing Noise

@NyanakoMeowani  Does the sound come through your headphones, or is it from the computer overall?  I ask because if the system is muted, it shouldn't be producing any sound that's sent through a sound output device.  One exception would be interference, so make sure no other electronics are close to your headphones or speakers.

If the sound is NOT coming through the headphones, it could be mechanical in origin, in which case the question is the source.  Try running Sims 4 with one side panel removed from the computer to see whether the source is inside.

The sounds stops when I unplug my earbuds, so I'm assuming it's coming from them.

@NyanakoMeowani  Does this happen with another pair of earbuds?  You could borrow a pair or dig up an old cheap pair you'd never otherwise use to test.  And to confirm, does the buzzing show up if you can hear Sims 4 through your speakers?  Does it happen with your main earbuds in other games?

I found an old pair of earbuds to test, but only one side worked so it was a bit hard to tell, but I don't think I heard any buzzing when using it.
And no, the buzzing does not happen in any other game with my main pair, it only happens with The Sims 4.

@NyanakoMeowani  Try looking for an update for the driver for these headphones and anything related.  Click Windows key-X, select the Device Manager, expand the Audio tab, click each device in turn, and click the green and black Update button.  Do the same for the Sound tab.  Windows may not find any new drivers, which is fine; the point is to check.  If something does install, restart your computer afterwards.

Aside from that, try playing with the sound settings.  I'm not great with sound issues, so I can't tell you exactly what changes in settings might help.  But with your headphones plugged in, right-click the sound icon in the lower-right corner of the screen, and try the various options you see under Spatial Sound.  Do this with the game closed, but you shouldn't have to restart your computer for the change to take effect.

You can also try the "Troubleshoot sound problems" option in the same right-click menu.  You don't need to sign in or contact Microsoft; the basic diagnostics can be run locally.  I don't know that anything will turn up, but it's worth trying.

Your headphones could still be the problem even if they only make the buzzing sound in Sims 4.  Maybe other games don't generate a particular sound (or data to be translated into sound), or the game uses the sound driver in some way that others don't.  If the above doesn't help, I don't know what else to suggest except using speakers or different headphones for now, and checking back after each Sims 4 update.