A friend I using the built-in motherboard Audio both had this sound pulse issue and with both of us it caused the game to freeze or crash. In my friends instance his machine would freeze first (audio would stop) then the Audio pulse would start moment later. His computer was a low spec (near the bottom system requirement). Mine was the opposite audio pulse would come first I would play for another 2-5 mins before a complete freeze of the game only (we both could Ctrl+Alt+Delete). My machine is much higher spec’d: Ivy Bridge i5 3570k w/ Nvidia GTX670. All of this only happened in WvW but we didn’t play much of the large event PvE which seems the other instance everyone has issue with.