I can't tell if she's hurting herself or having fun. It's a very loud squeak like I would assume something would make if it fell and said "ouch". Like a dog yelping. She's running around banking up the sides of the cage and she's made this sound about 10 times now. She keeps going even after she's made it (she doesn't stop and act injured). The closest thing I could find was on Youtube. It's very similar to this but it's only when she hits the sides of the cage as she's flying around. She just missed a jump up to her shelf (about 6" up) and made it when she landed. I'll try to catch it if I can and post a followup.
https://www.youtube.com/watch?v=Nht8x-egV7Y
https://www.youtube.com/watch?v=Nht8x-egV7Y