Elsewhere I ask whether it's sufficient to pray in a whisper. See there, please, for a description of whispering and how it differs from speaking quietly.
Answers to that question indicate that whispering prayers is sufficient. Those answers are IMO not completely convincing; nonetheless, let's suppose whispering prayers is, indeed, a fine way to pray.
My question now is about whispering while inhaling. It is possible — try it! — to whisper while inhaling: the same, or very nearly the same, sound issues as when whispering while exhaling. Would whispering while inhaling be a sufficient way to pray? (I suspect it may not count as speech or prayer, because the usual way of speaking is by means of exhalation.)
Any source or argument is most welcome.