Oh I'm going have to check that out - I'm a big fan of weird psycho-acoustic anything...I'm the guy who regularly hears very faint music in the white noise from a room fan, so I'm game.
Fans make all sorts of cool sounds, how could they not? I suppose somebody has made a "perfect" fan. I know Apple designers made a fan with intentionally unequally sized and angled blades because it is possible to reduce noise that way. I hear fan music too, and cars on the freeway music - if there are vibrations then there will be modulations of some sort.
I was messing about above, I haven't thought about what Craig mentions but it would be interesting if it was a "thing." Might be a way to use it somehow?