on learning new music

I'm learning some crazy/sexy/cool new music for an audition in 2 weeks.
One of the pieces I've learned and auditioned with before.
One of the pieces I have been listening to on repeat for the past few days and I LIKE it a lot and I "get" it.
One of the pieces I learned in one afternoon because it made sense in my head.
And the last piece (all from the same opera)...SOUNDS cool, LOOKS cool on the page, but isn't sticking in my head JUST yet.

It's so strange how sometimes things that sound brand new to the ear either stick with me or they don't.
It doesn't have to be tonal, it doesn't have to be pretty, it doesn't have to make sense--but I can't make sense of why I can learn something easily or not...and I'd really like to know how that part of my brain works!

For now-- staying near the keyboard, my iphone (with the mini-keyboard app--perfect for long train rides), the score, itunes, and any other media that can keep drilling all of this into my head.

I am not worried at all, I'm just wondering when that "click" will happen on the last piece and then I"ll know all of the excerpts that I want to know and all will be good throughout the land.