Many seem to be in agreement that "ascisco " (which does make perfect sense to me) may be the "hidden lyric". However, my interpretation is this:

Judith Marie has ascended, and it is the voice of God saying "MY SISTER"...welcoming her home.

Now this is what I hear without slowing or speeding up the recording, or doctoring it up with an audio editor, just good ol' fashioned headphones.

I'm probably wrong, but after listening to the long and mostly sad story told in the 3 parts of "Wings", it's rather conforting to picture the journey having a somewhat happy ending.