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Deixo aqui um sítio muito interessante. Um sítio para "aprender a fazer" o que quer que seja.
Neste caso transcrevo o artigo com o nome "How to Use a 7C Mouthpiece on Trumpet".
Para músicos como eu dá muito jeito.

The 7C trumpet mouthpiece is the most standard of mouthpieces. The cup and the rim are built so that your lips can endure longer playing than with a mouthpiece that has a deeper cup and a harder rim. Before mastering control of a 7C mouthpiece some basic exercises need to be performed. These include basic buzzing methods and repeated acclimation to the size of the cup.

Take your mouthpiece out of your case or the box. Press the mouthpiece against your lips and blow air into it. Avoid buzzing your lips and focus on a straight air stream. Hold the 7C mouthpiece in your strong hand and put the other hand behind the shaft. As you blow air into the cup pay attention to the velocity of the air as it hits your free hand. Blow with little force into the cup. Slowly increase the velocity of the air. You eventually want to feel the air temperature increase as it continues to hit your hand. This will tell you that your diaphragm is producing a higher volume of air as you progress.

Step
2
Take the mouthpiece away from your lips. You should not feel a tingling sensation. With the mouthpiece set aside, practice buzzing your lips. Simulate both long tones and scales. After about five minute of buzzing place the 7C back on your lips. This time you want to buzz inside the cup. Focus your air stream downwards as you blow. Take advantage of the soft curvature at the bottom of the cup. If you continue to aim your air stream in this direction it will make most pitches on the trumpet more stable.

Step
3
Attach the 7C mouthpiece to your trumpet. Pick any pitch above written C5 and sustain this note for at least 15 seconds. Proceed to descend down the chromatic scale, hold each pitch for the same amount of time, until you reach F#3. Play F#3 for at least ten seconds, repeating this five to six times or so. F#3 is the lowest regular note on the trumpet. The 7C mouthpiece is designed to play low notes with ease, but it does take some getting used to. Spend some extra time playing around in the low register until you feel comfortable.

Step
4
Put your trumpet and mouthpiece aside. Take your right hand and make a ring with your index finger and thumb. Use this ring as an imaginary mouthpiece cup and blow air through the middle of it. The object is to avoid hitting the inner rings of the circle with your air. You want the air to go directly in a straight line through the ring. This exercise will help to improve air direction accuracy and will allow your practice session to go much more smoothly with the 7C.