In a piano, dampers are movable mechanisms covered with felt that rests on the strings to prevent unwanted vibration of the strings. When the damper pedal is pressed, the dampers rise up off the strings, and a more resonant, sustained sound is achieved. A damper system is also used on other instruments such as the autoharp. The mute of a brass instrument.<br><br>A felt-topped strip of wood which, when in place on a piano string, keeps the string from vibrating.