I was doing some spatial audio recordings the other day and since then I’ve been wondering if it’s possible to design stereo ambiences using mono sources and stereo recordings and convert them to B-Format. For example, imagine that you are required to come up with an underwater or alien ambience on the fly — you can’t simply go outside and record. You have to create sounds specifically for those places.
How would you do that in VR? Should ambiences be spatialized or am I overthinking things?
I hope my questions make sense. Thanks!
yes this is possible & there are quite a couple of ways to do that. There’s The Ambisonic Toolkit  for Reaper & the AmbiX Plugin Suite  for instance which you can use in your DAW to create Ambisonic content from Mono/Stereo sources (both feature encoders & tools for positioning etc.). Or you could use Audio Middleware like Wwise to dynamically create Ambisonic Ambiances & record the output  (described further down the post).
Hope that helps!
In addition to the solutions already mentioned, if you want to do direct manipulation of your audio and place them into an ambisonic sound field then you can always use Max/MSP. External ambisonic objects have been written and you can always create your own bespoke systems. This paper details some of the principles and objects (http://quod.lib.umich.edu/cgi/p/pod/dod-idx/ambisonics-spatialization-tools-for-maxmsp.pdf?c=icmc;idno=bbp2372.2006.057) and I think the code is available of GitHub.