I have 2 deaf ferrets and I have trained them to come to me when I flick
the overhead light off and on.  They also feel vibrations on the floor
and smell food when I put it down (we have ceramic tile floors).  You
can also try a flashlight.  This works when they are awake or semi awake,
otherwise I have to go hunt them down.  They are all kept in one room,
so it is easier to find their hidey hole sleeping spot, that way I do
not have to panic, if I cannot find them.
 
Eleanor, Donald and the 6 pack of ferrets plus 2
[Posted in FML issue 5375]