For returning the duration of the given sound, in seconds.
Would be of course quite kewl if it supported all the possible ways you can have sound in the game: path to soundfile, CfgSounds/SFX/etc class, and so on.
_dur = soundDuration "A3\Sounds_F\sfx\alarm"; _dur = soundDuration "BattlefieldExplosions1_3D"; _dur = soundDuration "mp_groundsupport_05_casaborted_BHQ_0";