PERCUSSION INSTRUMENTS are a large group of instruments that produce sound by being struck, shaken, scraped, or clashed together. Most percussion instruments—such as the tam-tam (gong), cymbals, and maracas—do not have a definite pitch and are used for rhythm and impact, and the distinctive timber (color) of their sound. Other percussion instruments— such as the xylophone, vibraphone, and tubular bells—are tuned to a definite pitch and can play melody, harmony, and rhythms. The xylophone and vibraphone each have two rows of bars that are arranged in a similar way to the black and white keys of a piano. Metal tubes are suspended below the bars to amplify the
sound. The vibraphone has electrically operated fans that rotate in the tubes and produce a vibrato (wavering pitch) effect.
