Maintaining a good trumpet embouchure depends a great deal on the skill level of the person involved. Generally, there are a few simple rules regarding the posture of the chin and lips that can promote good embouchure. These techniques can help lead to higher levels of trumpet playing, especially concerning higher notes on the scale. While not all trumpet players may be able to reach the notes at the highest end of the instrument's range, all can maintain a good trumpet embouchure.
Perhaps one of the most overlooked parts of trumpet embouchure involves the positioning of the chin. When playing a trumpet, the chin should be kept as flat as possible. With the point of the chin pointing downward. This should be done in a way that does not restrict airflow from the lungs. This helps keep the lips and head in the proper position for playing the trumpet.
The other major factor in trumpet embouchure involves the lips. At a very minimum, the bottom lip should be curled slightly inward. In addition, the corners of the lips should be kept tight. This allows the trumpet player to possibly reach those higher notes. Trumpet players may think of keeping the corners of the lips tight by maintaining a flat smile.
Another key to good trumpet embouchure is making sure the teeth are kept slightly apart. Generally about a quarter of an inch. The easiest way to check this is to insert the shaft end of the trumpet mouthpiece between the teeth and have the teeth hold it there. That is approximately how wide the teeth should be apart when playing.
The cheeks also play a critical role in the embouchure for the trumpet. While many beginning trumpet players may be tempted to puff out the cheeks to accommodate for any backup in air flow, this is a bad habit. It promotes loose lips, which can have a bad effect on tone quality and range. Therefore, the cheeks should be kept as flat as possible when playing. This will also help make other muscles in the face stronger for trumpet playing.
The location of the mouthpiece is also an important consideration. Many beginners position the mouthpiece in the exact center point between the upper and lower lips. Keeping the mouthpiece mostly on the lower lip is a preferred method, however. One rule of thumb is to have the mouthpiece situated by two-thirds on the lower lip, and one-third on the upper lip. This is especially important when playing higher notes.