I just started getting the bug today It is the first time since game launch.. well actually ever I have had it happen to me. Because of this, it is defiantly a game bug and not a hardware or driver issue. I have completed many dragon fights before this without issue, it only started tonight with Teqault and Jormag. Same issue happens, sound cuts out followed by either a sine wave effect, or a client crash. As reported it is easily fixed by restarting the game, but it can throw you out of the game at the most inconvenient times.
….. just got thinking, is it possible that it could be an error-nous sound file crashing the Audio engine from a player equipping a certain item? Just seems strange that I only had this issue today when its been happening for months, and it always has the factor of a high population in the area when it happens.