Here is a question. If you tighten an E String on a guitar to tune it to say F# (not knowing guitar I assume you can tighten that much), when you strike the string with the pick do you have to strike it faster to make it play? Do you have to strike it harder? (I think so, though it may be so slight it would be hard to notice. . . Air speed would be analogous to the guitar pick . . . It has to have sufficient force to "pluck" the tighter string. Now the analogy has some holes. We've got "guitar strings" that have build in dampers "muscles" that can be used to slow down or stop the vibration . . . Help me on this because I'm working on this thought . . . the lips muscles are not used to vibrate the lips, but when we change pitches downward, I am assuming we dampen the vibration with our muscles in some way, and when we increase pitch, this would be why we have to give a bit of a push with air - to "excite the muscles" to the new frequency???