THAT is a photo of a trumpet bell resonating at a specific frequency. For pictures of the same bell and how it "vibrates" at different frequencies, please go to
http://vanadium.rollins.edu/~tmoore/research1.htm and click on the link "Physics of the trumpet". From there check out all of the links. The photo is from the first one.
A bit of review of those photos and some careful thought will quickly lead the viewer to consider the relative importance of the actual "bell vibration" (as contrasted with "air column vibration"), the coloring of the sound as a result of same, the potential for bell material/design/construction to effect the resonation, and the possibility of different bells to have totally different effects on the feedback and response that the player experiences!
Enjoy.
(Who says engineering doesn't have applications in the arts?)