I'm experiencing an issue with audio on the Open Beta and have confirmed I'm not an isolated case as multiple other players responded to an identical post on the Paradox forums. During the very start of a battle, after the deployment timer runs out, a very noticeable audio "popping" sound can be heard through my headset. It seems to be related to the engine noises of vehicles moving into position as zooming in and out on vehicles noticeably increases and decreases the sound itself.
It's quite annoying at the beginning of the battle but once combat starts, I believe it is mostly drowned out. I don't seem to notice after that point and can continue on playing the game. Thanks for taking the time in reading this post and hopefully the issue can be recreated for a fix.