A device that is fitted to an instrument to soften or otherwise alter its tone. This may be an object placed inside the bell of a brass instrument, or on the bridge of an orchestral string instrument.
In addition to reducing the volume of instruments, mutes change their timbre by suppressing certain harmonics associated with each instrument’s characteristic sound. Mutes came into widespread use in classical music in the 19th century, when romantic composers sought new timbres from the orchestra.
On string instruments, the mute is usually a small three-prong rubber or felt implement that attaches to the top of the bridge with one prong between each pair of strings. By restricting the vibration of the strings the mute attenuates higher harmonics, resulting in what most people perceive as a “darker” sound.
Many different mutes have been used on brass instruments but they all fit into or onto the bell. The common straight mute, a cone-shaped device that is gently force-fit into the bell, attenuates the fundamental pitch and lower harmonics, creating a metallic, almost nasal sound that can become very piercing at high volumes. French horn players often use their hands in the bell of their instrument to achieve a similar effect.
Other types of mute are cup mutes, similar to straight mutes, but with a large lip that forms a cup over the bell, resulting in a rounder, more muffled tone. Bucket mutes cover the entire bell and are filled with cotton or a similar substance, attenuating high harmonics and resulting in a soft, muffled tone. Wah-wah mutes are shaped like bowler hats and are opened and closed over the bell to produce their namesake sound. These were commonly used in 1920s jazz. Plungers (yes, unused rubber toilet plungers) are notable for their ability to produce sounds resembling the human voice. A non-musical example of this was the trombone that created the adults’ “voices” in the animated Peanuts cartoons.
Jazz trumpeters often use Harmon mutes – bulbous mutes with an adjustable cup on the front that creates a “buzzing” sawtooth-type sound. Miles Davis frequently used a Harmon mute with the cup removed, which resulted in his signature timbre.
Woodwind mutes are very uncommon, and in the case of the flute are almost completely unheard of. In rare cases when a clarinet or oboe is muted a handkerchief is usually stuffed up the bell, resulting in a muffled sound. Some bassoonists use mutes to regulate volume of extremely low or high pitches.
On guitars, “palm muting” is a technique executed by resting the heel of the picking hand lightly on the strings, close to the bridge to muffle the strings slightly, while simultaneously hitting the strings with the pick. This technique is used primarily on electric guitar, but it can also be useful for acoustic guitars. This technique is different from those for strings and brass in that it also results in a shortening of the notes played as well as altering the timbre.