<P> There are three major subgenres of bluegrass and one unofficial subgenre . Traditional bluegrass has musicians playing folk songs, tunes with simple traditional chord progressions, and using only acoustic instruments, with an example being Bill Monroe . Progressive bluegrass groups may use electric instruments and import songs from other genres, particularly rock & roll . Examples include Cadillac Sky and Bearfoot . "Bluegrass gospel" has emerged as a third subgenre, which uses Christian lyrics, soulful three - or four - part harmony singing, and sometimes the playing of instrumentals . A newer development in the bluegrass world is Neo-traditional bluegrass; exemplified by bands such as The Grascals and Mountain Heart, bands from this subgenre typically have more than one lead singer . Bluegrass music has attracted a diverse following worldwide . Bluegrass pioneer Bill Monroe characterized the genre as: "Scottish bagpipes and ole - time fiddlin' . It's Methodist and Holiness and Baptist . It's blues and jazz, and it has a high lonesome sound ." </P> <P> In the early years of the century, Wagnerian chromatic harmony was extended by opera composers such as Richard Strauss (Salome, 1905; Elektra, 1906--1908; Der Rosenkavalier, 1910; Ariadne auf Naxos, 1912; Die Frau ohne Schatten, 1917), Claude Debussy (Pelléas et Mélisande, 1902), Giacomo Puccini (Madama Butterfly, 1904; La fanciulla del West, 1910; Il trittico, 1918), Ferruccio Busoni (Doktor Faust, 1916, posthumously completed by his student Philipp Jarnach), Béla Bartók (Bluebeard's Castle, 1911--17), Leos Janáček (Jenůfa, 1904; Osud, 1907; Kát _́ a Kabanová, 1919 - 1921) and Hans Pfitzner (Palestrina, 1917). </P> <P> Further extension of the chromatic language finally broke with tonality and moved into the style of atonal music in the early operas of Arnold Schoenberg (Erwartung, 1909; Die glückliche Hand, 1912) and his student Alban Berg (Wozzeck, 1925), both of whom adopted twelve - tone technique for their later operas: Schoenberg's Moses und Aron, and Berg's Lulu . Neither of these operas were completed in their composers' lifetimes, however, so that the first completed opera using the twelve - tone technique was Karl V (1938) by Ernst Krenek . </P> <P> Some of the most important operas of the twenties and thirties were composed by the Russian Dmitri Shostakovich (The Nose, 1928 and Ledi Makbet Mtsenkovo Uyezda (Lady Macbeth of the Mtsensk District), 1932). </P>

Name several eastern ideas that impacted art music composition in america in the twentieth century