I've not noticed a buzz. Have you tried deleting and repatching the sound .HOGG? I can't imagine that could hurt. Not sure if it's a solution, but it's an idea. In case you decide to try, here is the path to take on a windows machine.
c drive > Cryptic Studios > Star Trek Online > Live > Piggs
From there, the file you would look for is called sound.HOGG
If you delete it and then start the game client, it will automatically repatch the HOGG for you. That file is quite large though (well over 1gig) so it will take time to patch.
A simpler solution might have something to do with your speakers themselves! I am sure you've though about that though.
I had buzzing also, then my sound went out completely.
I exited the game, restarted the computer, force verified then tried to log in. I began hanging a few millimeters left of the C in cryptic on that screen. I mean hanging for ten minutes or more before I had to a hard shutdown of my PC. That happened about four times in a row, hanging right before the C at precisely the same spot. All other programs/games worked that I tried.
Next I tried a system restore, and went back in time a week. No change, still hung on the Cryptic load screen.
Yesterday I tried a full reinstall, and that got me back in. I have not had any strange or failed audio yet. Fingers crossed.
This is the only game I've played on this PC that can make me lose audio completely, requiring I restart my PC. It's happened probably ten times or so over a couple years but had never been preceded by the buzzing noise previously.
I have a buzz too. How ever it only happens from doing Starfleet Base Defence.
I'm getting at some points massive sound lags and if it getting bad enough the game never returns to a normal state once getting out of instance. And i will need to reboot computer to fix it.
Other times in same. I get looping voice even leaving instance and need to close client to fix it.