This got me to thinking: why don't Irish musicians play this way? And then I quickly realized that playing this way effectively takes a lot of embouchure control and makes staying in tune very difficult, and I assumed that was the answer. You need to have your lip in an incredibly precise point, and the slightest imperfection will screw up the tuning or make the instrument squeak.
But then I had another idea: why not have a ring that goes over the head-joint, that can be pushed in and out with the lips to partially cover the fipple? Well, I decided to make one out of tape. And...my goodness. I can literally double the first-octave volume of my Oriole. It's louder than a Chieftain. But if I want to go into the second octave, I just pull the tape ring back with my lips, and it jumps right into the second octave, no louder than normal. So...I can play louder in the first octave than in the second.
![boggle :boggle:](./images/smilies/icon_boggling_local.gif)
Now, of course, I'm not going to be able to play anything fast with my makeshift tape design. But I'm sure that if I had the proper tools, I could make something that was more effective out of metal - something spring-loaded - that would allow me to tighten my lips or loosen them just a bit to move the ring up and down and partially cover/uncover the windway. Tightening your lips would push the ring just an infinitesimal amount forward, preventing the octave break and allowing you to "push" the bottom octave to its maximum volume (without going sharp! that's the best part). Meanwhile, the second octave could be played no louder than normal when the lips are loosened.
Why doesn't anyone do this? It might be a bit harder to play than a normal whistle, but man, would this be useful for sessions if you mastered it! I really wish I had the tools needed to experiment with this.