A mute is a device attached to a musical instrument which changes the instrument's tone quality (timbre) or lowers its volume. Mutes are commonly used on string and brass instruments, especially the trumpet and trombone, and are occasionally used on woodwinds. Their effect is mostly intended for artistic use, but they can also allow players to practice discreetly. Muting can also be done by hand, as in the case of palm muting a guitar or grasping a triangle to dampen its sound.

Mutes on brass instruments are typically inserted into the flared end of the instrument (bell). They can also be held in front of or clipped onto the bell. Of brass mutes, the "straight mute" is the most common and is frequently used in classical and jazz music, but a wide variety are available. On string instruments of the violin family, mutes are usually attached to the bridge, the piece of wood that supports the strings. Palm muting a guitar involves placing the side of the hand across the strings, and some of them have physical mutes which produce a similar effect. Pianos have a soft pedal and occasionally a practice pedal, which both decrease the instrument's volume.