In the 20th century, composers have continued to write string quartets. Claude Debussy (1862-1918) and Maurice Ravel (1875-1934) each wrote one. Arnold Schoenberg even added a voice to his first String Quartet. Béla Bartók (1881-1945) wrote six string quartets which are very hard to play. They have very exciting rhythms which often come from his native Hungarian folk music, as well as complex harmonies. Dmitri Shostakovich (1906-1975) wrote fifteen and Benjamin Britten (1913-1976) wrote three.