#1
So I've been learning Apocalyptic Love by Slash. I'm able to tab the song but these two parts which include wah are extremely hard to recognise, at least for me. In the beginning there's that short wah starting and then in the middle of the song there's a longer wah part just before the solo.

Why is it so hard to recognise the notes when it comes to the wah parts ._.
#2
That's a very interesting inquiry in the field of Psychoacoustics
"Yeees I am your god!" John Petrucci, Phsyco excercises