Hey there Rod, thanks for your continued enthusiasm, great work ethic and cool questions.
So when you say “there seems to be a particular amount of air that is necessary to match what’s coming back from the horn for higher notes to sound” – do you mean any note at all or a sustained note? Do you mean a long note or a short note? You can play double C’s with no activation in below the neck whatsoever, they will just be really short and not mega loud.
OK, so “now when I go e to g on lip slurs – g is as hi as I can go with minimum (small but there) push” suggest a longer phrase so the body needs to get involved. How much it needs to get involved is the big question. As I said in a podcast yesterday you may not have yet heard, apparently about 2% of the energy we expell gets emitted into the room as sound. The rest is lost to friction against the pipe wall or keeping the soundwave energised.
Don’t go thinking I am a physics expert, I am nowhere near that, but just a couple of simple ideas made a big difference to me.
You ask “Is matching the horns acoustic waves and our pressure waves (even if fully passive breath is achieved – the breath out is what im calling pressure) all up to the face/mouth aperture, or will we learn something about breathing” – Depends on the dynamic of the desired note. The body will become involved BUT does the Body’s Concert Hall shut down. It’s that tight rope mentality.
It sounds like you are still backing up a bit so the balance between flow and tension is not optimum net. Steps 3-6 of the Presto Singing C Series should answer this question for you.
I hope that helps.