Since plenty of us have access to the same source Brian does, I had a listen. Boosted the relevant lines a couple of times, but obviously couldn't get the piano down. Track 11 was slightly clearer than track 10, but I couldn't actually be confident that the first two lines were unchanged to the final version. Line three sounded like "is this a feeling" although I suspect my brain was autocompleting the first two words". For line four the piano was too loud for my ears to establish anything other than a hint of there being vocals.
I imagine that it would be very difficult to come up with a filter that reduced the piano to further isolate the vocal line, and if Brian wants to know, he has better tools than I do with which to find out.
What is (hopefully) good about this is that it's likely to trigger a bunch of follow up questions about multitracks that at least gets the subject back in to his mind.