How about the size of the trumpet
 The choice of the aperture size of the trumpet is mostly related to the area of lip vibration. A large aperture will increase the area of lip vibration, so it is easier to play large volume. But it is not necessary to use a large mouth to play a large volume, small mouth can also, depending on whether the mouth and musical instruments can match properly. The purpose of the mouthpiece is to enable the player to control the instrument under comfortable conditions. Too large a mouthpiece is easy to fatigue the player, and avoiding too deep a mouthpiece is the same. Usually the tone darkens and loses its original brightness after lip fatigue. Shallow mouth may initially make people feel sharp as if there is no thickness, habit will highlight its advantages. Not only is it easy to keep the sound bright for a long time, the clear sound comes from the uniform spectrum of the overtone, but the shallow blow is easier to do than the deep blow under the normal blowing force. I think a good trumpet tone is a clear and light sound, too heavy or too deep to avoid. So when the novice first chooses to blow the mouth, if you try a series of blows that seem to be available but at a loss, the shallow blow only makes the high sound easier to blow, but does not increase your range. Where your extreme ability goes, the result is the same with deep or shallow blowouts.