A violin mute is a small device, usually made of wood, leather or rubber, with slots in it spaced to accommodate the strings. A violinist places a mute over the bridge of the violin to dampen the sound made by the strings. The mute increases the mass of the bridge, which has the effect of reducing the amplitude of the vibrations and limiting audible harmonics. There are two main types of violin mute, each of which serves a different purpose.
An orchestral mute, also known as a sordino, is a small mute used in performance. By placing the mute over the bridge, the violinist reduces the overtones produced by the strings, giving the violin a smoother, more mellow sound. In performance, the orchestral mute produces a hushed effect, especially when used by all the violins in a string section. The musical direction "con sordina," or "con sord," indicates that a mute is to be used. Danish composer Carl Nielsen recommended a specific type of wooden violin mute for performances of his music.
There are two types of orchestral violin mute. The clamp type is detachable and can be placed on the bridge and removed. The sliding type attaches permanently to the strings. When a sliding mute is not in use, the violinist leaves it attached to the strings between the bridge and tailpiece of the violin.
A practice mute, also known as a hotel mute, is a larger mute which is seldom used in performance. While the orchestral mute dampens the sound of the violin, the practice mute dampens it even further. Violinists who want to practice in crowded areas such as apartment buildings and hotels sometimes use a practice mute to avoid disturbing their neighbors.
In addition to a violin mute, violinists who want to practice without disturbing others sometimes use a mute violin, a violin with no soundbox or with a very small soundbox. Since they lack a soundbox, mute violins do not amplify the sound made by the vibrating strings. This produces a thin, quiet sound, allowing the violinist to tell if his or her playing is correct but not disturbing other listeners. Violins of this type have existed since the 18th century.
Other stringed instruments can also use mutes, which resemble violin mutes. Like violin mutes, they fit over the bridge, dampening the vibrations and quieting the sound of the instrument. Instruments which use mutes include the cello and the viola.