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FWIW, my understanding of the unfurling concept is that as we contract the aperture corners inwards, towards the Air Column / center of the mouthpiece, the lips move forward into /against the mouthpiece and the lips somewhat unfurl/pucker. This is little by little, but of course is significant over a large interval. The vibration of the lips happens within the aperture itself, the part of the lips that touch the air column.

Claude Gordon talked a bit about this, showing the diagram of the circle and he and Clarke talked about the lips contracting towards the center of the mouthpiece as we ascend.

The muscles in our face can appear to be pulling back, like we’re smiling as we ascend; however, this is opposite to what is truly happening–we are in fact contracting our aperture corners inwards towards the center of the mouthpiece / air column, which reduces the size of the aperture.

This is different than what some people, like myself, who previously understood that we should thin out or lips, roll them in and perhaps even actively buzz them against the mouthpiece to produce the sound.

If we, however, take a good breath and release the air, the energy of the air moving through a small aperture (if we have an efficient shape, with the vibrating surface as relaxed/loose as possible and the only engagement surrounding the aperture), the energy released into the mouthpiece, instrument, causes the lip tissue to vibrate and the sound wave is created.

The concept of scrunching up the lips and contracting them forwards towards the mouthpiece seemed foreign to me when I first started playing that way; but it works so much better than how I used to play.

I don’t recall a video specific on that but will post a link to one if I think of it if Greg doesn’t get to it.

Hope that helps. Best, John.