I can see where some people would get the idea that ferrets think "prey!"
when they hear high pitched noises, and this may be partly true.  But I
don't believe it is the whole truth, at least not for all ferrets.  My
friends and I between us have fifteen ferrets (I have six).  While most of
our ferrets are not really bothered by high-pitched noises, two of theirs
will become very agitated when a certain hamburger toy is squeaked.  Ginger
and Kiwi will run over and bite the person squeaking the toy (usually), then
take it away and hide it.  They seem very protective of the hamburger, which
is why I don't think it can be wholly a prey thing.  And if you tease Ginger
by not letting her have the hamburger IMMEDIENTLY (I'm not the pain-loving,
masochistic idiot who does this, Jim does it sometimes) she will bite you
HARD.  Kiwi put a twist on this one time when she came and took the
hamburger away, went and hid it, THEN came back and bit the person squeaking
the hamburger.  Kiwi will also climb your body to get to the hamburger.
[Posted in FML issue 2240]