What's with that weird electric/hissing sound coming from under the MacBook Air keyboard?

Question

Audio

Good evening.
Yesterday, while working in silence, I noticed a small hissing/electrical sound. Heard from under the keyboard. It didn't seem to happen before, or maybe I just didn't notice it.
Is this normal? What makes that sound?
PS Macbook Air. Laptop in idle mode.

Answer 1

Cooler, what else. Once you hear it in idle mode, it means that the laptop is thoroughly dusty, you need to go to the service and clean everything, well, or try to blow it yourself with something.