What is the primary function of the plunger mute in brass instruments?

The primary function of the plunger mute in brass instruments is to partially open and close the bell, which allows for unique tonal effects. This mute is typically held in place by the player's hand and can be adjusted to create different sound qualities and dynamics. By moving the mute in and out of the bell, performers can achieve a variety of sounds, ranging from muted to more open, resonant tones. This characteristic makes it a popular choice for adding expressive techniques during performances, particularly in jazz and contemporary music contexts.

In addition to its primary function, some brass players can use the plunger mute to create a less defined sound, which contributes to the improvisational aspects often found in jazz music. This ability to manipulate the space of the bell enhances the overall expressiveness of the instrument, aligning it with the mood of the piece being performed.