I discovered this when monkeys playing with the ball threw it onto some walls and scared me.
If you drop a monkey ball right next to a wall it will make a horrible noise which I would imagine is the impact sound repeating itself over and over again.
From what I can tell this can happen on anything that has collisions with the item but it's the easiest to reproduce with walls.
It should also be noted that standing on top of the ball item while it is inside the walls will produce this noise as well.
Steps to Reproduce
Make a U shape with walls and place the ball inside the curve as close to the back wall as possible.
This issue has been fixed in either a future version or updated in a previous version.