Twentieth Century and Beyond
Many labels have been used to describe music of the twentieth and twenty-first centuries. Labels such as neo-romantic, atonality, avant-garde, contemporary classical, minimalist, serial, aleatory, microtonal, new simplicity, postmodern, etc. have been used to describe a wide range of creative output produced over the last hundred years or so.
Arguably the most important composer of the twentieth century is the Russian born Igor Stravinsky. Stravinsky's career contains three periods. His first period is marked by nationalistic works, the second by a preoccupation with classical forms (neo-classicism), and the third by a radical departure into serial music.
Around 1903, expressionism developed in Vienna. This style reacted against the ponderous romantic compositions of the nineteenth-century. The Second Viennese School was largely responsible for the development of expressionism. They were a group of composers guided by the musical theories of Arnold Schoenberg. During the early part of the century, Schoenberg and his disciples Alban Berg and Anton Webern experimented with atonality, and beginning in 1923, twelve-tone serial music.
Atonal music does not contain a tonal center or key. Nor is it concerned with harmonic function. Its central concern is to produce an equality among all of the pitches in a musical passage, which results in a removal of the musical gravity or magnetism that is caused by traditional keys and scales, thereby creating a different sense of “expression.” Serial music, however, attempts to give structure to free atonality. In simple terms, serial music uses fixed “tone rows” or “sets” of notes as the basis for a musical composition. All twelve chromatic pitches are organized in a non-tonal (key/scale) sequence and presented in that order without any repetition until all twelve notes have sounded.
The avant-garde movement, led by John Cage, further questioned traditional definitions of music. Cage has been described as a revolutionary who developed music based on chance or indeterminacy. Using unusual instruments and sometimes non-instruments, or found instruments, Cage created a body of work that challenged the very notion of sound itself. One of his pieces, 4'33,” asks the performer to sit in silence for four minutes and thirty-three seconds. During the piece, the random noises in the performance space become the music. This may seem like a silly idea, but there is also something quite groundbreaking and brilliant about this concept.
During the expressionist and avant-garde movements, western tonality never went away. In fact, American composers Aaron Copland, George Gershwin, Leonard Bernstein, Gian Carlo Menotti, and Samuel Barber kept tonal music alive and well during the twentieth century. Drawing from their Romantic predecessors, and in some cases American folk and jazz music, these composers produced indelible works (symphonies, chamber pieces, operas, musicals, and film scores) that will likely stand the test of time. Among these pieces are Barber's Adagio for Strings, Copland's Fanfare for the Common Man and Appalachian Spring, George Gershwin's Rhapsody in Blue and Porgy and Bess, Bernstein's West Side Story, and Menotti's Amahl and the Night Visitors.

