mouthpiece
The part of a wind or brass instrument that the player blows into or across.
In Depth
The mouthpiece is the critical interface between the player and the instrument. Brass mouthpieces are cup-shaped metal pieces with a rim, cup, throat, and backbore. Woodwind mouthpieces vary: clarinets and saxophones use a mouthpiece with a single reed clamped to it, while flutes have an embouchure plate with a blow hole.
Mouthpiece selection dramatically affects tone quality, range, comfort, and endurance. Brass players may own dozens of mouthpieces for different situations — a shallow cup for high notes, a deep cup for dark tone, a wide rim for comfort. Professional musicians often spend years finding their ideal mouthpiece, and many are fiercely loyal to a specific model.
Louis Armstrong played on the same Bach 7C trumpet mouthpiece for most of his career — a relatively small, standard mouthpiece that he used to produce one of the most recognisable sounds in music history.