HELP: Hissing sound while on external view flyby - how to check integrity on non-Steam install

[jokerBR]

Hello fellas, after the last (or previous) update, my BoS has a constant "hiss" sound when looking the plane from the outside while flying (F2) or flyby (F3). Inside the cockpit or without the engine running is all fine. I guess some audio file got corrupted. Is there a way to check the integrity of game files on a NON STEAM install?

Cheers

[jokerBR]

Well, it seems that the trick is to just delete the UPDATE folder and run the updater. After that I had to redo graph/audio settings, but the problem is solved.