On string instruments of the violin family, the mute takes the form of a device attached to the bridge of the instrument, dampening vibrations and resulting in a "softer" sound. Usually this takes the form of a small three-prong implement which is attached to the top of the bridge with one prong between each pair of strings, although anything which stops the bridge vibrating will suffice, and sprung clothes pegs, for example, have been used. The late Karl Haas told a story (supposedly true) about a violinist in an orchestra having a confectioner make him a mute entirely from candy, so that he could surprise his desk partner by eating the mute after finishing with it.
A famous use of string mutes is in the introduction of Prokofiev's Romeo and Juliet. All the strings are muted (con sordini) so the sound appears to grow out of the initial dischord, as if appearing from nothing. The sound is softer and more lyrical and flowing.
A more modern invention is a mute which sits on the strings between the bridge and tailpiece of the instrument. This is slid into place right next to the bridge to produce the same effect as the detachable three-pronged mutes.
Heavy "practice mutes" or "hotel mutes" are available for string instruments. These also fix onto the bridge of the instrument and reduce its loudness. Recently, practice mutes have become rather common in contemporary music, appearing in works as diverse as those by John Corigliano and Gérard Grisey.
On the cello a wolf mute is often attached to the G-string between the bridge and the tailpiece. This does not change the timbre of the instrument on the whole, but helps to eliminate the wolf tone which is found on many cellos around a sixth or seventh above the open G-string. When used to eliminate wolf tones on a double bass, it is often attached on the A-string.
The violin mute was first described by Marin Mersenne in 1636. One of the earliest examples in the use of muted string instruments is found in Act II of Jean-Baptiste Lully's Armide, when the entire string section sporadically plays with mutes. However, the use of mutes did not become widespread in classical music until the 19th century when romantic composers sought new timbres from the orchestra. By the 20th century the use of mutes was common.
On the guitar, a player may palm mute their guitar. To palm mute, the player uses the side of their hand, or the edge of their palm, closest to the bridge to cover the strings. This shortens the sustain significantly causing a muting effect. This is a very common technique in rock guitar.
A variety of mutes have been used on brass instruments, all of which either squeeze inside the bell of the instrument, or are hung or clipped to the outside of the bell. These mutes are typically made out of aluminum, brass, or copper metal, but more economical plaster, cardboard, and plastic versions exist. Each material produces a distinctive sound.
The most common type is the straight mute, a hollow, cone-shaped mute that fits into the bell of the instrument. This results in a more metallic, sometimes nasal sound, and when played at loud volumes can result in a very piercing note. Straight mutes have small pieces of cork attached to the end that squeeze against the inside of the bell and hold the mute in place. Straight mutes are available for most brass instruments, including the tuba.
The second common brass mute is the cup mute. Cup mutes are similar to straight mutes, but attached to the end of the mute's cone is a large lip that forms a cup over the bell. The result is removal of the upper and lower frequencies and a rounder, more muffled tone.
The solo-tone mute (labeled by the Humes and Berg Corporation as the "Clear-Tone" mute) is shaped like a long straight mute, and includes sound baffles inside the mute that accentuate treble frequencies. It is rarely written for today but was common in jazz ensemble music written between 1930 and 1950. The most trademark use of the "solo-tone" mute was in Tommy Dorsey's trombone solo in "Song of India," recorded in 1944.
The buzz-wah mute is shaped like a cup but is designed with vibrating membranes on the mute, as if several kazoos were attached to the instrument. This mute creates a very unusual and recognizable sound, but is quite difficult to play, and is extremely rare in performance. In the early 1920s, Joseph 'King' Oliver was known to hold a kazoo in the bell of his cornet to achieve the buzz effect. Commercial versions of this type of mute soon followed. The earliest patented version being of this was by Guy B. Humes in the mid 1920s.
The Wah-wah mute (also known by the brand name Harmon), is a hollow, bulbous mute in two parts. Unlike the more common straight or cup mutes, the Harmon mute has a solid ring of cork that completely blocks all of the air leaving the bell, and forces all of the instrument's air column into the mute. In a hole on the front of the mute there is a cup on a tube that can be slid in or out, or removed completely, depending on the composer's direction or the player's preference. The mute produces a sound perhaps best described as a highish-pitched 'buzz'. Harmon mutes are available for many brass instruments, but are only commonly used by trumpets and trombones. Miles Davis often played through a Harmon mute without the stem; this greatly shaped the character of his sound, and greatly influenced the jazz community in such classic tracks as "All Blues". A famous example of Harmon mute coupled with hand muting on trombone is the teacher's voice in the animated Peanuts cartoons.
Bucket mutes attach to the rim of the bell with springs and contain cotton or a similar substance. The effect is removal of high frequencies and a soft, muffled tone. Some modern bucket mutes (by JoRal for example) are designed as over sized straight mutes filled with batting, with large holes in along the side. These are held in the bell of the instrument with strips of cork, like straight and cup mutes, to make their use more convenient; players often find the spring-style mutes awkward for quick passages.
Derby Mutes or hat mutes (also known as Bowler Hats, and also confusingly called Wah-wah mutes) were common in jazz from the 1920s when King Oliver played and others wrote for them. These mutes were originally actual bowler hats. In the 1920s with the advent of aluminum as an art metal, derby mutes were stamped out of metal by companies such as Meta-Lite, Elton, and Harmon. These replaced the use of the actual bowler derbies. From the 1950s to the present derby mutes were made of fibre (a resin impregnated cardboard). They are still available form the Humes & Berg Company. Derby mutes are typically mounted on stands in front of the trumpet and trombone players, to permit quick movement of the bell in and out of the hat quickly, although they can be opened and closed over the bell of the instrument by hand. These mutes have fallen somewhat out of favor in recent years, as bucket mutes or playing in to the music stand can give a somewhat similar sound.
Stop or Stopping mutes are unique to the French horn. The term hand-stopping involves the hornist inserting his/her hand into the bell of the instrument, completely cutting off the airflow. A buzzing sound results, and the tone is raised a semitone from the shortening of the effective length of the instrument. At lower intervals, application of this technique is very demanding. At the pedal level, it is nearly impossible (as in the final movement of Tchaikovsky's Symphony no. 6). To remedy this, a small mute made of brass, with a small branch and tiny brass bell, is substituted for the hand. It still takes an enormous amount of air to achieve the "stopped" sound, but is certainly possible for an experienced player. Stop mutes have traditionally transposed the muted notes, but a line of non-transposing stop mutes have recently been developed in Japan.
Plungers are simply unused rubber toilet plungers, sometimes with a hole drilled in the location of the removed shaft. They are often used in a manner similar to the hat mute, where the musician manipulates the plunger in front of the bell while playing with their other hand. A "closed" plunger gives a tone similar to a tightly inserted cup mute, and a skilled plunger technician can often produce sounds startlingly similar to the human voice. In Duke Ellington's orchestra, trombonist Tricky Sam Nanton was noted for his work with the "plumber's friend". The Glenn Miller band made a wooden red and white plunger popularly called the "Tuxedo Plunger" (used in the band's hit tune "Tuxedo Junction"). For a combination of straight mute sound with the readily manipulated plunger Pixie mutes are used. More recently, some players use a plunger made from a dog toy called the "Jolly Ball Tug-n'-Toss" cut in half.
Practice mutes, also known as Whispa, whisper, or hotel mutes, are similar to straight mutes in appearance, but have a solid ring of cork that prevents air from escaping from the bell like a Harmon mute. There are sound baffles inside the mute, and tiny holes in the sides of the mute that allow air to escape silently. These mutes are extremely quiet and are rarely used in performance. They are usually used for privacy and to avoid disturbing bystanders during practice sessions. Yamaha makes an electronic practice mute system marketed as Silent Brass. By way of a microphone, the system equalizes the sounds and sends the signals to a headphone jack on the mute.
Mutes will usually make the instrument play sharp. High quality mutes try to reduce intonation issues while maintaining the characteristic sound. Even so, it is often necessary for the musician to accommodate by adjusting the tuning slide.
There exist saxophone mutes which are usually made of a soft material (such as velvet, silk or chenille) woven around a hard inner ring (usually brass or plastic). This mute is placed in the bell, most commonly perpendicularly to the body of the saxophone. This softens the tones of the saxophone somewhat, and can be useful in classical settings as it also dampens the sound a bit. They are not in common use, but they are not rare either. They are usually only made for the alto saxophone, although bigger and smaller ones can be made and used for higher and lower registers of saxophone. Some companies currently produce mutes that cover the entirety of the instrument (such as the E-Sax Whisper mute and the Silent Sax case), thus dramatically diminishing the volume of sound produced. To date their overall effectiveness is still in question.
For the Snare Drum, the Tenor Drums, or even most of the Drum (Trap) Set, a "pad" is available for practice purposes. This is a piece of rubber that is laid on top of the drum head, which mutes the drum for a volume better suited to indoor or home practice.
Traditionally, a military band playing for a funeral would cover the drums with cloth, producing a muffled tone suitable to the solemn occasion.
Indication that the soft pedal should be used is the instruction una corda or sometimes due corde, with tre corde or sometimes tutte le corde cancelling it. On early pianos it was possible by use of the soft pedal to play only one, two, or all three strings, making the distinction between una corda (one string) and due corde (two strings) meaningful; but this is no longer the case.
It used to be common for pianos to be fitted with another kind of mute: a piece of felt or similar material which would sit between the hammers and the strings. This results in a very muffled and much quieter sound. It was not used in any serious context, but was useful for reducing the volume of the instrument when practicing and was often termed a "Practice Pedal". Few pianos, apart from some uprights, have this device today.
To confuse matters, the instruction senza sordino (or some variant) is sometimes used to indicate continuous application of the sustain pedal on a piano, throughout a long section or an entire movement (as opposed to the standard use of , or alternatively a brace mark, written below the staff, for short applications of the pedal). The "sordino" of this notation refers to the felt dampers, each of which stops the sound of a note's strings when the note is not being played. When all the dampers are lifted by the sustain pedal (senza sordino), all the strings of the piano are allowed to sound, resulting in a complex sound when all strings are free to sound sympathetically with other strings. (See Moonlight Sonata for a classic example of senza sordino.)
A piano tuner will use another kind of mute with a piano; a rubber or felt wedge, which is inserted between strings to make sure only the desired string in a "unison" (that is, in the strings for one note) is sounding. A felt strip can also be inserted and "braided" between strings, to mute several strings at once.