Yeah... it's funny, in playing French Horn I always had trouble with notes that were "out" of my vocal range, even though the Horn was actually a 5th lower than the notes on the page! I could play the exact same range of "paper notes" on a Trumpet even though it was a different range of actual notes and actual places in the harmonic scale than the Horn. Anything above the g at the top of the staff and I'd be having trouble. So visualization really is a large part of it.