A: ODEON will complain when the loss of rays is more than 20% and the calculations will be terminated. Ideally a room should be watertight. Otherwise the software cannot know the path that each ray follows. If a ray escapes from the room there is not any reflection point or any information for its successive course. When there is loss but it is lower than 20% ODEON accepts the geometry since the missing energy is not so much to deteriorate the accuracy.