Frequently, I'll use breath attacks when practicing easy slurs in the staff -- feels like breathing into the horn. Along with that, I'll speed up the air or increase the volume of air (that's what it feels like but don't really know which is occuring) to ascend to the next partial. Disclaimer: I do not know what really is happening anatomically: lungs, tongue, aperture, lips, corners. I can ascend a partial also using my chops rather than air speed/volume. When I slur using air, my aperture feels as if it stays roughly the same diameter. When I use my chops it feels as if it does become smaller as I ascend. Disclaimer (again): never measured. A long time ago, I noticed that using air speed/volume (don't really know which it is) to slur is a bit more difficult. Also operating on the very suspect notion that more = better. So, I began using that method during practice a good deal speculating "If I can negotiate slurs using air rather than chops would make slurring easier when using chops. What does conventional wisdom say about this air thing and chops thing? Final note, I'm really not aching to know what my body is doing. When I play during band, I don't have a zillion thoughts zipping about. I'm listening to the music about me endeavoring to play in tune and in time. You know, give the guy with the stick what he wants.