Gee! You make me blush, Robin! Thanks!! I only have a couple of questions left now: 1) If I put a rigid wall in front of the bell, I would say that the bell was Closed, since I see the wall as some "closed door". This is not the only way that one could reason about it. One could say that when there´s a rigid wall in front of the bell, the bell is in fact Open since it it "more open than the rigid wall". Which do you mean when you say that the bell is Open, and what would you say that the bell is if a rigid wall is in front of it, Robin? 2) If you, like me, would call a bell with a rigid wall in front of it Closed, and since we know that a rigid wall is a heavier media than air which will place the wall impedance at the far right in the Smith chart, a conclusion must be that a bell is Closed when the air inside the trumpet meets a media with Higher impedance than itself. Since the air inside a tube generally has Higher impedance, we have the opposite situation; the air inside the trumpet meets a media (the outside air) with a Lower impedance than itself. Since this is the opposite of the Closed situation, doesn´t this actually imply that the bell is Open? 3) Normally when a "thinner" media with lower impedance meets a "thicker" media with higher impedance wave Pressure is High in that interface while wave Speed is Low. I would have thought that in the case of a trumpet the inner air has High impedance and the outer air has Low impedance. In this case the wave Pressure would be Low and the wave Speed would be High. Which is true as far as the trumpet is concerned? 4) Are you saying that due to partials or other things, the air impedance inside the trumpet is Complex (in a mathematical sense), and that this is the thing that makes the bell Closed although some things (like the ones above) are pointing towards that it is not? It is true that the air pressure inside the trumpet is very high and that the air in there can show some Complex behaviour, but is this the physical explanation to why the bell is Closed instead of Open, as you see it? I´m not at all sure that you´re saying this, just asking! If, however, you´re not saying this, what then is it that makes my reasoning why the bell is Open not hold water? It is also true that in the extreeme high register the high notes will be projected out of the bell so efficiently that (almost) no energy is reflected back into the trumpet. The trumpet will act as a megaphone for these high notes, and the notes will simply be amplified versions of the mouthpiece buzzing. In this high register total matching between trumpet and outer air is at hand, I should think, so this could not be a case of Open bell. Instead it should be a case of Totally Matched bell. But, in the "normal" range, what is it that makes my reasoning why the bell is Open not hold water? I´m sure you can explain this, and my only goal here is really to understand the trumpet better!! Thanks for taking the time to help me!