At the Schoeps MikroForum 2018, Hyunkook Lee (Senior Lecturer in Music Technology and the Leader of the Applied Psychoacoustics Lab (APL) at the University of Huddersfield, UK) gave a presentation discussing psychoacoustics in a 3D sound context which included some fascinating information about vertical localisation for 3D and immersive sound recording formats. A key note is that there is little in terms of time difference concerns for vertical/height channels for recording and that actually using coincident techniques for vertical channels has some benefits, meaning there is little need to create tall microphone arrays when using directional microphones appropriately.
Watch the presentation on Youtube if you’re an audio nerd like me who is interested in surround recording techniques: