This problem is NOT a GW2 problem but a hardware problem. I’m having the same issue (with my SB X-Fi Titanium Fatal1ty Champion) and it’s cause by magnetic interference from other devices/cards in your PC. If you ‘listen carefully’ to this noise, you’ll hear difference when you have more HDD and/or GPU usage.
WRONG. This is NOT what he describes.
What we are experiencing is a sound cut-out, with a simple tone with an amplitude LFO of about 2 seconds cycle time. Others have reported it with onboard sound cards, as well as dedicated cards (and not just ones made by Creative)
I have had this horrible sound issue also and I use an Audigy. It’s not the driver or the card, NONE of my other games have sound problems and I have hundreds. There is some sort of issue with the sound engine in GW2.