That's definitely not normal behaviour. Might be a grounding problem or a bad charger.
Did you try plugging it into another wall socket and see if it makes the same buzzing sound?
Normal
All lg charger has trafo inside it
My ex lg phone (og gpro n4) always has sound while charging
Sent from my LG-D802 using xda app-developers app
No, it's not normal. Mine doesn't do that. No charger i've ever had buzzed while charging.
"All lg charger has trafo inside it"..what does this mean anyway?
Wrong. Its not trafo or dynamo thats causing the sound. Its because the charger is kharab. You can fix it by buying a new charger.