The vibraphone was invented in the United States in 1921. The vibraphone quickly became popular as a jazz instrument and it is primarily used in this style. The jazz great Lionel Hampton is synonymous with the vibraphone. The bars are made of alloy and the notes have a sustaining quality. Fans at the top of each resonator are rotated by a spindle activated by an electric motor which results in a sustained vibrato. This instrument is widely seen with three octaves. The damper pedal on this instrument has a different function than other mallet instruments – the damper stops the sound. The vibraphone is played with mallets with ends made of yarn.