Three years ago I had a house built. From the blueprint I could conceptually see the roof, room sizes, landscaping, etc., but not until the house was completed could I actually observe the beauty of the design from the blueprint. In much the same way, the audience receives the full emotion of the performance based on what they hear, not on what is on the printed page. From the first music lesson we are taught that one note on the printed page is higher or lower than another. This is simply not true.
Higher notes are actually faster frequencies.
On the beach when the wind blows through a crack in a rock we hear the pitch go up with the velocity of the wind. A clear sound is easily attained in all registers when the velocity of relaxed air creates the upper register and not the stiffness of the embouchure. Most importantly, build all registers slowly and securely. If we practice too fast initially our mind develops the bad habit of not picking out all the details, resulting in reading, rhythm and accuracy problems. Slow down when practicing and let your mind see all there is to see.