the past for inspiration and wrote works that draw elements (form, harmony, melody, structure) from it. This type of music thus became labelled neoclassicism. Igor Stravinsky (Pulcinella), Sergei Prokofiev (Classical Symphony), Ravel (Le Tombeau de Couperin), Manuel de Falla (El retablo de maese Pedro) and Paul Hindemith (Symphony: Mathis der Maler) all produced neoclassical works. Italian composers such as Francesco Balilla Pratella and Luigi Russolo developed musical Futurism. This style often tried to recreate everyday sounds and place them in a "Futurist" context. The "Machine Music" of George Antheil (starting with his Second Sonata, "The Airplane") and Alexander Mosolov (most notoriously his Iron Foundry) developed out of this. The process of extending musical vocabulary by exploring all available tones was pushed further by the use of Microtones in works by Charles Ives, Julián Carrillo, Alois Hába, John Foulds, Ivan Wyschnegradsky, Harry Partch and Mildred Couper among many others. Microtones are those intervals that are smaller than a semitone; human voices and unfretted strings can easily produce them by going in between the "normal" notes, but other instruments will have more difficulty—the piano and organ have no way of producing them at all, aside from retuning and/or major reconstruction. In the 1940s and 50s composers, notably Pierre Schaeffer, started to explore the application of technology to music in musique concrète. The term electroacoustic music was later coined to include all forms of music involving magnetic tape, computers, synthesizers, multimedia, and other electronic devices and techniques. Live electronic music uses live electronic sounds within a performance (as opposed to preprocessed sounds that are overdubbed during a performance), John Cage's Cartridge Music being an early example. Spectral music (Gérard Grisey and Tristan Murail) is a further development of electroacoustic music that uses analyses of sound spectra to create music. Cage, Berio, Boulez, Milton Babbitt, Luigi Nono and Edgard Varèse all wrote electroacoustic music. From the early 1950s onwards, Cage introduced elements of chance into his music. Process music (Karlheinz Stockhausen Prozession, Aus den sieben Tagen; and Steve Reich Piano Phase, Clapping Music) explores a particular process which is essentially laid bare in the work. The term experimental music was coined by Cage to describe works that produce unpredictable results, according to the definition "an experimental action is one the outcome of which is not foreseen". The term is also used to describe music within specific genres that pushes against their boundaries or definitions,