When learning to play trombone, the mouth shape can be simply explained as the position where the trombone mouth is placed on the lips when learning to play trombone. On the basis of this theory, the mouth shape can be divided into three types:No. 1. The size of the mouth accounts for two-thirds of the upper lip and one-third of the lower lip. 2. The nozzle accounts for one-third of the upper lip and two-thirds of the lower lip (less on the top and more on the bottom). 3. Mouth 1 occupies half of the upper lip and half of the lower lip. Because everyone's lips are different in size and thickness, and their teeth are arranged neatly, everyone's horn mouth is in a different position on his mouth when playing trombone. Therefore, trombone learners can choose any of the above three mouths when choosing and adopting the mouth shape, without having to decide which one, because there are many excellent trombone players in the world today who use these three mouths. In classical, modern and jazz music, trombone players are required to play different pitches and timbres, and any lip type can be played perfectly. However, trombone players with difficult playing skills do not mean that * * * all adopt a mouth shape as the best playing mouth shape, and each mouth shape can play the above music form well. In the long-term teaching and playing, I think that the mouth shape of trombone beginners is basically selected and gradually fixed after learning to play trombone for about two weeks. Of course, it is also related to its own conditions. Many people have good conditions, neat teeth, and generally have a straight mouth and will not miss. Trombone learners should be reminded that it is not advisable to tilt their mouths to one side. Because the best pronunciation point of our lips is the center of the lips, not the sides. However, some people have irregular teeth or poor lip conditions, which leads to crooked mouths and trumpet playing. This requires us to go to the stomatological hospital for dental plastic surgery as soon as possible under the guidance of professional teachers, which is conducive to playing trombone well. Of course, a mouth with a horn can also play, but it is difficult to be an excellent trombone player. And the cost is more than others, but the learning result is not ideal. Therefore, it is best to straighten the horn mouth by straightening the teeth and make full use of the best pronunciation point in the center of the lips, so as to play the most full and concentrated beautiful timbre of the trombone. When we play trombone (as do other wind instruments), once the mouth shape has been selected and fixed, the breath will be placed in the most important position (I will focus on breath in my next article "Breathing"). Our lips are just sounding tools, vibrating under the blowing of qi, just like the whistle of clarinet and oboe, vibrating and sounding under the action of qi. Therefore, trombone learners don't have to study, think about it or change their tune frequently. Even if you change your mouth, you should do it under the guidance of a professional teacher. Don't change their mouths at will. Because there are too many examples of failure in this field, a few people neglect their studies because of changing their mouths.