Particularly in the early part of the century, many composers wrote music which was an extension of 19th century Romantic music. Harmony, though sometimes complex, was tonal, and traditional instrumental groupings such as the orchestra and string quartet remained the most usual. Traditional forms such as the symphony and concerto remained in use.
Many prominent composers — among them Béla Bartók, Dmitri Shostakovich and Benjamin Britten — made significant advances in style and technique while still employing a melodic, harmonic, structural and textural language which was related to that of the 19th century and quite accessible to the average listener.
Music along these lines was written throughout the 20th century, and continues to be written today. Some other twentieth-century composers of works in a more-or-less-traditional idiom include
Jean Sibelius,
Alexander Scriabin,
Ralph Vaughan Williams,
Sergei Rachmaninov,
Gustav Holst,
Igor Stravinsky,
Sergei Prokofiev,
George Gershwin,
Roy Harris,
Aaron Copland,
Aram Khachaturian,
Colin McPhee,
Howard Hanson,
Alan Hovhaness,
John Corigliano,
Henryk Gorecki, and
Leonard Bernstein.
Minimalist composers such as Philip Glass can also be said to retain nineteenth-century melodic and harmonic language, but depart radically in structure and texture.
Many other 20th century composers took more experimental routes.
Arnold Schoenberg is one of the most significant figures in 20th century music. His early works are in a late Romantic style, influenced by Richard Wagner and Gustav Mahler, but he later abandoned a tonal framework altogether, instead writing freely atonal music (he is often reckoned to have been the first composer to have done so). In time, he developed the twelve-tone technique of composition, intended to be a replacement for traditional tonal pitch organisation. His pupils Anton Webern and Alban Berg also developed and furthered the use of the twelve-tone system and were notable for their use of the technique in their own right. They together are known, colloquially, as the Schoenberg "trinity" or the Second Viennese School.
Schoenberg's music and that of his followers was very controversial in its day, and remains so to some degree now. Many listeners found (and still find) his music hard to follow, lacking a sense of definite melody. Nontheless, works such as Pierrot Lunaire are regarded as classics of the 20th century, and the style he pioneered was very influential. Many composers have since written music which does not rely on traditional tonality.
The twelve-tone technique itself was later adapted by other composers to control aspects of music other than the pitch of the notes (such as dynamics and methods of attack), creating completely serialised music. Milton Babbitt created his time point system, where the distance in time between attack points for the notes is serialized also, while some composers serialized aspects such as register or dynamics. The "pointillistic" style of Webern — in which individual sounds are carefully placed within the piece such that each has importance — was very influential in the years following World War II among composers such as Pierre Boulez and Karlheinz Stockhausen. Ironically, after years of unpopularity, the twelve tone technique became the norm in Europe during the 50's and 60's, but then experience a backlash as generations of younger and older composers returned to writing tonal music, either in a neoclassical, romantic, or minimalist vein. Stravinsky, originally studied with Nikolay Rimsky-Korsakov, became a modernist, then a neoclassicist, became a twelve tone serialist upon Schoenberg's death.
Many composers also began to look to the past for inspiration in a trend called neoclassicism. Modernists such as Igor Stravinsky and Paul Hindemith, reacting against romanticism and even their own modernism, began to write for smaller ensembles using simpler textures and clear "classical" formal models.
John Cage is another prominent figure in 20th century music. Cage questioned the very definition of music in his pieces, and stressed that all sounds are essentially music. Cage in the "silent" 4'33" presents us with the idea that the unintentional sounds are just as musically valid as the sounds originating from an instrument. Cage also notably used aleatoric music, and found sounds in order to create an interesting and different type of music.
Cage, though, has been seen by some to be too avant-garde in his approach; for this reason, many find his music unappealing. Interestingly, the seeming opposite of Cage's indeterminism is the overdetermined music of the serialists, which both schools have noted produce similar sounding pieces, yet many serialists, such as Pierre Boulez and Karlheinz Stockhausen have used aleatoric processes. Michael Nyman argues in Experimental Music that minimalism was a reaction to and made possible by both serialism and indeterminism.
See also experimental music
Many composers in the later 20th century began to explore what is now called minimalism. Minimalism in music may be summarized as music created from small melodic, harmonic or rhythmic ideas and using small or gradual variations to add interest to the music.
Notable composers who used these minimalistic ideas were Terry Riley, Philip Glass, Steve Reich, and La Monte Young. Riley is seen by some as the "father" of minimalistic music with In C, a work comprised of melodic cells that each pefromer in an ensemble plays through at their own rate. Steve Reich in his early works wrote in a minimalistic fashion, but began to depart from strict minimalism and explored many other contemporary musical ideas.
Minimalistic music is often contentious amongst traditional listeners. Critics find minimalistic music to be overly repetitive and empty while proponents argue that the static elements that are often prevelant draw more interest to small changes. Minimalism has, however, inspired and influenced many composers not usually labeled "minimalist" such as Karlheinz Stockhausen and Gyorgy Ligeti. Composers such as Arvo Pärt and Henryk Górecki, whose Symphony No. 3 was the highest selling classical album of the 90s, have found great success with what has been called "Holy Minimalism" in their deeply felt religious works.
Main article: Electronic art music
Technological advances in the 20th century enabled composers to use electronic means of producing sound. This took several forms: some composers simply incorporated electronic instruments into relatively conventional pieces. Olivier Messiaen, for example, used the ondes martenot in a number of works.
Other composers abandoned conventional instruments and used magnetic tape to create music, recording sounds and then manipulating them in some way. Pierre Schaeffer was the pioneer of such music, termed musique concrete. Some figures, such as Karlheinz Stockhausen, used purely electronic means to create their work. In the United States of America, Milton Babbitt used the RCA Mark II Synthesizer to create music. Sometimes such electronic music was combined with more conventional instruments, Stockhausen's Hymnen and Edgar Varčse's Déserts offering two examples (although Déserts is sometimes performed today without the tape part).
Composers such as Alvin Lucier, Gordon Mumma, and David Tudor created and performed live electronic music, often designing their own electronics or using tape.
A number of institutions sprung up in the 20th century specialising in electronic music, with IRCAM in Paris perhaps the best known.Romantic style
The Schoenberg "Trinity", atonality and serialism
Modernism
In the early part of the 20th century modernist composers such as George Antheil and others produced music that was shocking to audiences of the time for its disregard or flaunting of musical conventions. Charles Ives quoted popular music, often had multiple or bitonal layers of music, and extereme dissonance and seemingly unplayable rhythmic complexity. Henry Cowell performed his solo piano pieces by strumming or plucking the inside of the piano, knocking on the outside, or depressing tone clusters with his arms or boards. Edgard Varese wrote highly dissonant pieces which utilized unusual sonorities and futuristic, scientific sounding names and dreamed of producing music electronicly. Charles Seeger enunciated the concept of dissonant counterpoint, a technique used by Carl Ruggles, Ruth Crawford-Seeger, and others. Igor Stravinsky and Serge Diaghilev fled the riot that greeted The Rite of Spring and Vaslav Nijinsky's choreography. Darius Milhaud and Paul Hindemith explored bitonality. Kurt Weill wrote the popular Threepenny Opera entirely in the popular idiom of German cabarets. Modernist composers being the avant-garde, they often wrote atonally, sometimes explored twelve tone technique, used liberal amounts of dissonance, quoted or imitated popular music, or somehow provoked their audience.Nationalism and Neoclassicism
As in the 19th century, many composers looked to the popular or folk music of their native countries for material or inspiration as feelings of nationalism grew in all areas. Modernists such as Béla Bartók, Zoltán Kodály, and Leoš Janáček collected and studied their native Hungarian folk music which then influenced their compositions.Cage and music in the everyday
Minimalistic ideals
Electronic music