I have the exact same issue, sounds like the re-verb is way to high in the stations ambient. .
I aggree. I thought it was the ambient noise on the promonade, it seems to decrease as you head further out from the centre, it dissapears entirely buy the time you get just over the threshold of the shipyard area, turn around walk back up the slope and it comes back. I've put a ticket in as well.
I've only been having this same issue since the patch on Feb 2, 2012. I also have a 7.1 headset. Razer Megalodon to be exact. The noise has actually been giving me nausea and vertigo so I just turn the volume off and take my headset off while I'm on DS9. Still needs to be fixed because #1 Its a potential health hazard and #2 it can seriously damage speakers.
I also experience this issue. If it helps the developers, my soundcard is a Xonar Essence STX. My onboard sound is disabled.
HOWEVER I worked out how to fix the issue for myself. On my Xonar Control Panel, if I set the Audio Channels field to '2 channels', '4 channels' or '6 channels' the buzzing noise stops.
I originally had this set to 8 channels and have had no buzzing issues anywhere else in Star Trek Online or any other game.
To anyone trying this solution, for me when I changed the channels I had to restart the game as all the in-game audio would stop when I changed the Audio Channels setting whilst the game was running.
Also, when the buzzing noise is in effect, it seems to change as you move around the Promenade indicating it may be a particular background sound that is being distorted. I can hear other Deep Space 9 sounds above the distortion.
I've tried switching from surround to stereo as suggested in previous posts, I will try the channels next but I don't have the same card or headset. Thanks for the idea though! This stuff is killing me!
It does not happen if I use onboard sound currently.