I get audio static too. It happens always when the music track changes, never mid-song. A workaround is to save, exit to main menu (at which point the static goes away) and load the savegame. I know... works in geoscape only. Using XP Pro, Creative XtremeGamer soundcard, drivers maybe few months old. All audio settings at default (ingame, OS, soundcard software settings). At least they should be... ffdshow codec pack installed. And Winamp. In case this that is helpful somehow. Game version at 2.2.1.
EDIT: Oh, and the static always goes away when the music track changes again.