Mouthpiece (brass) Mouthpiece (brass) On brass instruments the mouthpiece is the part of the instrument placed on the player's lips. The mouthpiece is a simple circular opening that leads, via a semi-spherical or conical cavity, to the main body of the instrument. Mouthpieces vary to suit the tone of the instrument. Lower instruments also have larger mouthpieces, to maximize resonance (see pitch of brass instruments). Also, mouthpieces are selected to suit the embouchure of the player, to produce a certain timbre, or to optimize the instrument for certain playing styles. For example, trumpet and trombone mouthpieces are usually semi-spherical whereas French horn
French horn the time, the mouthpiece is placed in the exact center of the lips, but, because of differences in the formation of the lips and teeth of different players, some tend to play with the mouthpiece slightly off center. Although the exact side-to-side placement of the mouthpiece varies for most horn players, the up-and-down placement of the mouthpiece is generally two-thirds on the upper lip and one-third on the lower lip. When playing higher notes, the majority of players exert a small degree of additional pressure on the lips using the mouthpiece. However, this is undesirable from the perspective of both