Singing Mice

So mice can sing. I've often wondered what you'd hear if you recorded ambient sounds and frequency-shifted them. What groans do buildings make, or trees? And what is that noise behind the baseboards? This also seems to solve a puzzle that's annoyed me for years. Remember the footage of a fox hopping through deep snow, stopping, and then rearing up to dive in and fetch up a mouse? The narrator would always say something like "the fox's sensitive hearing can distinguish the movements of a mouse under 6 inches of snow." I always thought that was a bit extreme: snow's a pretty good muffler. But if the mouse was singing . . .