Using musical note frequencies reminds me of a trick used by an old gear
design engineer I knew.
When we were having problems with a noisy gearbox he would call for the
engineering blueprints, ask for the gearbox to be run up to speed and
then produce an old harmonica from his pocket and  start playing up and
down the scales until he got a note which matched the offending noise.
He'd then check the speed, consult the blueprints to find the numbers of
teeth on the various gearwheels and point to a gear on the drawing and
say "that one's the problem gentlemen" - he was invariably right.
Of course we younsters could achieve the same thing given half a day and
£10 000 worth of electronic analysis equipment.
So get out your harmonicas and harmonise with them wing beats.

Alan Riach
Bathgate