Analogue correlation circuit to measure water flow in a pipe?

[ratstar]

A bit of a diversion:
One of the best I have heard is an assisted reverb system demo in a music venue, where a pitch shifter was included in each reverb path. So the room provided a sort of harmony to anything going on, Not really something to do long term, but interesting to hear.

Thats your ears doing the magic instead of the machine.