So most of us have experienced the difference in the intervalic distance of partials as we move to higher registers. However, for me, as I move to higher range I find it harder to do lip slurs. I might not be using my tongue properly, but it just feels like it requires so much effort, and I wonder how lip trills and shakes are ever going to really enter the equation at this point. I don't have any real issues with flexibility in my middle/lower ranges (but still can't move quickly in those). Any suggestions?