Like the "terrors of the year 1000" which seem never to have happened (though there might have been some local disturbances around the year 1030) or the 1754-ish "calendar riots" in Bristol, which seem never to have happened (though the calendar reform may have been an election issue, and there may have been election related violence in some places), or the Council of Nicea "setting" the rule for Easter (it didn't; as far as I can tell it merely stated that all the provinces should follow a uniform rule, without specifying what the rule would be). The idea of the "banned", "devil's tritone", as far as I can figure, contains a kernel of truth: the leap of a diminished 5th or augmented 4th was rare. Some music seems to use the B-flat to avoid having three successive whole tones. But I so far can't find any evidence of even a single prelate telling his choir "don't sing that interval or I'll excommunicate you". There may have been one, but I haven't found him yet.

T.