buzzing sound coming from your power adapter

Hi,
I just got my mac a few days ago but for the first time, I used the extended cable to connect up my macbook. I notice a buzzing noise coming from the adapter that is very audible not loud but you can hear it. Is this normal? when i press my ear against the adapter it gets louder.

call apple.

sounds like a hardware defect.

thanks, its getting really annoying

been onhold for 15 minutes already, is this typical?