I have the Sony Xperia E and when I charge my phone it makes a buzzing noise which I can only hear if I put my ear to it. I ordered a new one and it does exactly the same thing. I charged my phone using the USB cord plugged into laptop but it takes hours to charge and I need my phone due to having children in school. I've tried charger in all sockets in my house and it does it in every single one. Will it still be ok to use as it chargers phone fine.