There is so much talk online about the high register being all about air velocity, or as Doug explained, it’s really about the shape of the mouth cavity and tongue placement (I hope I got that right, Doug). I’ll admit that my brain is my biggest impediment because I just can’t wrap my head around how to do it. I get the concept, but it feels utterly foreign in practice. In my current state the only way I feel like I can go higher is with more pressure, and, yes, I know that’s wrong.
Another thing that I find baffling is people who can lip buzz (no mouthpiece) through their full range. I can’t do it at all. I guess it’s important to be able to do that, so I’m not sure I’ll ever truly be able to get it together again. What’s really hard about coming back to something I used to do well is that I never had to even think about many aspects of technique when I was younger. It all developed naturally over time. As you get older your thinking becomes more critical and analytical (though there is ample proof these days that many people never experience that...just watch the news, or 95% of the embarrassingly stupid videos on YouTube, or the Idiocracy that is our government). However, that too can be another impediment for some of us. You know what they say about old dogs and new tricks, right?
I’m just trying to get some chops back to play for fun, not profit, my life and livelihood are not dependent on being good anymore, thank god! My advice to anyone under 25, do not stop playing. It’s much easier learning to do this the first time than the second!!