I think I had this problem back when I upgraded to Windows 10, and I solved it. The problem is - I don't remember how.
I had to make a fresh reset of Windows 10 on my laptop, and now I have a problem with my speakers. After some time working on the computer, my left speaker, and only the left one, begins to softly crackle. It sounds like very distant fireworks. As time goes on, the crackling becomes more and more intense, eventually turning into some sort of whirr - like a tiny gnome is drilling my laptop from the inside. There is no vibration of any kind, but eventually the noise is a constant whirring that gets louder and louder, to the point where I genuinely worry that my laptop will explode. This happens especially when I'm playing games that are very demanding from the laptop, but sometimes it just occurs during browsing web or even typing Word documents. Once it starts, there is no stopping it - it gets faster and louder until I turn off the computer, or at least put it into sleep mode. If I plug in headphones, the normal sound switches to them, as expected, but this horrible crackling remains in the left built-in speaker.
I've tried downloading new drivers, I tried deleting Realtek drivers and using Windows defaults, I tried installing older version of the Realtek drivers, I've read that it might be connected to the touchpad and tried disabling the touchpad. The worst thing that I know I solved it some time back - through some kind of magic, probably, - but I cannot remember how.
Edit: This is what it sounds when it starts. And this is what it sounds once it gets going. This is most definitely not the fan, it's the left speaker.
