Most of the stuff posted in this thread are just plain wrong. The trumpet does not amplify what is coming out of the mouthpiece. A trumpet works MUCH differently. The same goes for the pitch on the mouthpiece with and without the horn Two completely different things are happening. The sound coming out of the bell is only partially related to what comes out of the mouthpiece. When we play a note into the mouthpiece and horn, we basically just get a standing wave going in the horn (kind of like the note that you get blowing on the top of a bottle). That standing wave normally is determined by the laws of physics and can be any of the notes that we can play without changing the valves. Which note that we get has a lot to do with how strong that our chops are. This is because that standing wave does fight back a little and weak chops can't overcome it. If the horn just amplified, we would have no "slots" and none of the characteristic trumpet brilliance. When we play the pedal note C, that is one wavelength in the whole horn. Our low C is 2 wavelengths, G is 3, 3rd space C is 4, E is 5, G is 6, Bb above the staff is 7 and high C is 8 wavelengths. The ONLY things that buzzing on a mouthpiece are good for is ear training and just getting the blood flowing. It is of no direct benefit to more accurately playing specific pitches as the standing wave and the lips reaction to it determine the success. You have to practice with the horn to train that fine motor reaction.