Ducted fan sound
I would say if you think the sound of a gnat with its ass on fire sounds great then by all means you will love the sound of a ducted fan!
Seriously, if you want to hear ducted fans those old SKS tapes have tons of them. If you happen to be in the Phila, PA area stop by and I'll give you all my old ones (tapes that is, I don't have any ducted fans!)