How a Trumpet Mute Works

What is a Mute?

While several orchestral instruments in different families use devices known as "mutes," those used by trumpets and other brass instruments are unique. Though the name of this object suggests that it is used to make an instrument's sound softer (and this is generally the predominant purpose of mutes used in other instrument families), the biggest change a brass mute generally makes to an instrument's sound is in timbre, not volume.

Shape and Materials

Different trumpet mutes have somewhat different shapes, but they are almost all a variation on a variety of a hollow, conical plug inserted into the bell of the instrument. Mutes may be made of brass, copper or aluminum, but they may also be made of types of reinforced cardboard or, occasionally, plastic. In general, metal mutes are considered to have the highest sound quality and best resonance though this may not always be the case with certain types of mute. The mute is held in place by pieces of cork, glued to the end of the cone which press against the inside of the trumpet's bell, just as a cork stays put when wedged inside a wine bottle.

A mute must not completely plug the bell of the instrument, as this would prevent air flow and make playing impossible. Instead, a mute allows air to flow either around itself through gaps between the cork pieces that hold the cone in place or through the hole in the center of the mute.

Altering Sound

Each mute changes the sound of the trumpet when it is attached to the bell by altering the resonance of the tone, just as the trumpet produces its tone by manipulating the sound made by the player's buzzing lips as it resonates through the instrument. A mute changes the shape of the instrument and therefore, its acoustic qualities. By being attached to the trumpet, the mute absorbs some of the acoustic vibrations, dampening the volume while adding its own distinctive quality of vibration to the trumpet's sound.

Types of Mute

The most basic type of mute is a straight mute, which is simply a hollow cone with an open top (like an empty bottle). This mute makes the trumpet's sound more piercing and nasal in quality.

Other mutes are often variations on the straight mute shape or additions to it.

Another common mute, the cup mute, is basically a straight mute with an attached cup or lip at the bottom which further muffles the sound and creates a "buzzing" sound quality from the vibration of the lip. A wah-wah mute (often identified by the common brand name, "Harmon") is a mute that plugs the trumpet completely except for a hole in its center, limiting the resonance of the trumpet to a quiet, piercing and high frequency tone. The sound may also be affected by inserting a hollow metal stem into the center hole and sliding it in and out like the slide of a trombone, or by covering and uncovering the hole with a hand or plunger to start and stop the sound of the trumpet in quick bursts.

Many other types of mutes exist, though some of these are uncommon, obscure or hard to obtain. New mutes or muting techniques are often invented by composers and instrumentalists daily, which may become widely popular or may never be tried again. All serve the purpose of creating different special sounds for the brass instrument.