I found the "sweet spot" My trumpet teacher had told me about this many years ago, and I finally discovered what he was trying to teach to me, all along. It reminds me of the Movie.., "The Jerk" with Steve Martin, when he finds out about his "Special purpose" and writes home about it. lol! The aperture is the smooth part of the lips that open first, as you are gently blowing air, through your "pursed" lips. I learned about it from "Charlie" on the internet, and Wow.., what a difference it makes, when you center your Mpc. over this opening, and then you begin to learn how to "lip slur" your notes, by drawing in your upper lip, while tightening your abdominals. My range is now,, PHENOMENAL!!! Thanks Charlie!!