This issue might be what M1sfit has reported in this ticket, currently closed: http://feedback.arma3.com/view.php?id=2824
It's some kind of positional noise/buzzing sound that pops up from time to time, encountered both on Stratis and Altis (meaning it's apparent on dev build as well). I tried messing around with sample rate, but with no luck. I also tried to use my motherboard's soundcard instead of my main one (even tried to reinstall drivers), and still, the problem persisted. From what I get, it's possible that the problem is apparent only on my end, but would like to know if anyone else has it, and if possible, to be fixed.
GTX 660 oc
Line 6 toneport ux2 soundcard
(To clarify: I've encountered this issue only on Arma 3 -nowhere else.)