All the chamber walls are covered with sound-absorbing material which renders the walls acoustically invisible and hence why I said "No walls."
You don't need reflections to measure the omni-directional effect because the effect is "encoded" within the curves. When you place the LFR in a room, the speakers interact with the room and the omni-directional effect within the curves is decoded thanks to your ears-brain system in that room.
The Listening Window is (traditionally) a mean of the curves I described but as I said, Axiom may be extending the angles to more fully characterize the speaker response.
