[sdiy] NE572

[Cornutt, David K]

I (finally!) took an inventory of my parts stock last night.
And in the process, I came across an old NE572, still in the
Rat Shack blister pack (that's how I know it's old).  I've never
done anything with one of these, and I don't recall what I
might have bought it for.  But it looks like something that might
be fun to play with.

So, I was looking over some search results for circuits that
use this part, and I came across a Phillips patent for some type
of psychoaccoustic circuit that uses the 572.  As near as I
can tell, it provides a very short (5 ms) emphasis to high
frequencies in the input signal, when the signal crosses a
certain level threshold.  The patent says nothing about what
this actually does, in terms of perception, other than that it
is an "attractive effect".  

So I'm trying to get my head wrapped around what this actually
sounds like, and what it might be good for in a synth context.
Anyone ever come across an implementation of this?