Weird ringing noise from my PC monitor?

Sometimes, when I open a look at a certain thing in Windows my monitor makes a weird, persistent ringing noise. It’s not exactly loud but it’s clearly audible to anyone nearby.

I can replicate the noise by opening up Notepad++ and dumping in a big binary file (like a data file from a PC game). Immediately, I hear this very strange buzzy, ringing noise coming from my monitor. If I close the file or look at a normal text file, the noise goes away.

Why would this be? I noticed it also happens when I open certain sections of Microsoft Outlook while using remote desktop at my job.

What kind of monitor?

CRT monitors can make a high pitched noise. under certain conditions, like lots of white in the image, it might be more so.

knowing what kind of monitor would help provide a better answer.

It’s a 4-year old 28" LCD monitor from ViewSonic. The funny thing is, the weird noise is repeatable and happens under certain circumstances, but the circumstances are rarely graphically demanding, nor particularly bright or dark!

Turn off your background noise, the buzzing is relatively quiet. I bet you’ll hear something with yours.

Amazing. That link generated the sound but in more of a whooshing manner. I’d love if someone could explain the science behind this.

Also, this noise is loud enough that there’s no way I wouldn’t notice it, even with a bit of background noise. It’s still fairly quiet but definitely very noticeable.

The electrical load on the monitor’s power supply changes depending on the image it is displaying.
The power supply is an oscillator - it switches on and off very rapidly. The waveform of the oscillations changes due to the varying load, and that ends up being audible (usually a transformer acts as a very poor speaker).