(Updated again: there was a readability problem in the previous document. This version should be better).
I have the pleasure of presenting this work by Henrik, one of our forum contributors with serious scientific credentials. (Henrik, along with Bernie Hutchins, played a major role in developing the new version of our Hum Map Survey). It is a logic flow diagram that sorts out the logic and decision making regarding the source of the Worldwide Hum. It will prove valuable for scientists new to the phenomenon, those who are scientifically literate, and those who have already invested time and energy into this issue.