A vibraphone is a tuned percussion keyboard musical instrument that contains a set of aluminum bars that are struck with two or four felt or wool-covered mallets. A different pitch is obtained from each bar because of differences in their width and through the grinding away of material from underside in an arch shape. The bars are suspended by a cord that passes through a hole drilled through their width.
A major difference between the vibraphone and other mallet instruments is that under each bar is a resonator tube, usually made from aluminum and with a butterfly valve at the top. The valves are linked together on a common axle which is connected to an electric motor, which, when activated to rotate the axle, causes the tubes to produce a tremolo effect. The sound can also be modified by a sustain pedal somewhat similar to that of a piano.
The standard modern vibraphone has a range of three octaves, from the F below middle C, although four-octave models have been becoming more common. Unlike the xylophone, it is a non-transposing instrument, generally written at concert pitch. Another differences from the xylophone is its soft, mellow sound, in contrast to the brighter, crisper sound of the xylophone.
The vibraphone is is a standard instrument in the percussion section of modern orchestras and concert bands and is the second most popular solo keyboard percussion instrument in classical music, after the marimba. It is also frequently used in jazz.