Laptop makes loud buzzing sound randomly?!

I've recently bought a new laptop, a HP Pavilion np something but its a decent little mid-range machine. I've had it less than a month and its already making random buzzing sounds during audio playback (whether this be iTunes, YouTube etc it doesnt matter, does it for them all). Does anyone have any ideas how I can fix this?

PS operating system is windows 8, don't know if this will make a difference.