Ringing sound when charging?

I plugged in my Meizu and it started ringing. It wasn't very loud, so I thought at first my ears were ringing for some reason. But no, because somebody else who was there could hear it too. I unplugged it and turned it on, and it stopped. Now I plugged it in again to put some music on it, and it started making a weird squealy sound, and it's louder then before. Other persons comment: "Sounds like my car stalling or something."
Edit: I have dropped it a couple times though, not very far though except for once. >_>
Edit 2: It didn't make any bad sounds when I charged it with a cell phone charger. O_o;;

The power transformer you are using must be broken. Always check the specifications of the transformer to make sure it can handle the current of electricity at your country.