this is how you make a Environment sound,
class CfgEnvSounds
{
   sounds[] = {asound};
   class asound
   {
      name = "asound";
      sound[] = {"soundfile.ogg", db+0, 1.0};
      soundNight[]={"SoundFileCanBeDifferent.ogg", db+0, 1.0};
      titles[] = {};
   };
};
but it still plays everywhere once its started.