Although theoretically any object could be used to prepare a piano, in practical application preparation objects are usually expected to have certain characteristics:
They are applied directly to the piano strings;
They must fit in the desired location inside the piano;
They (usually) should not move from their location during playing;
They must be reversible (that is, when a properly prepared piano has been "unprepared", it should be impossible for anyone to tell that it had ever been prepared; no permanent damage is done to the piano).
Additionally, most preparations will change the timbre of the string in such a way that the original pitch of the string will no longer be perceptible, though there are occasional exceptions to this.
In his Ragamalika (1912–22), based on the classical music of India, French composer Maurice Delage (1879–1961) calls for a piece of cardboard to be placed under the B♭ in the second line of the bass clef to dampen the sound, imitating the sound of an Indian drum.
In 1922, American composer Henry Cowell (1897–1965) pioneered a technique he dubbed "string piano", which involved having the pianist reach inside the piano and pluck, sweep, scrape, thump, and otherwise manipulate the strings directly, rather than using the keyboard. He developed these techniques in pieces such as Aeolian Harp (1923) and The Banshee (1925). Although Cowell's techniques don't call for placing objects (other than the hands) inside the piano, John Cage frequently cited Cowell's work as the primary inspiration for his development of the prepared piano.
In his Chôros No. 8, a 1925 work for two pianos and large orchestra, Heitor Villa-Lobos added to his score instructions to the pianist to insert pieces of paper between the strings and the hammers to attain a certain sonority.
The invention of the "prepared piano", per se, is usually traced to John Cage. Cage first prepared a piano when he was commissioned to write music for Bacchanale, a dance by Syvilla Fort in 1938. For some time previously, Cage had been writing exclusively for a percussion ensemble, but the hall where Fort’s dance was to be staged had no room for a percussion group. The only instrument available was a single grand piano. After some consideration, Cage said that he realized it was possible “to place in the hands of a single pianist the equivalent of an entire percussion orchestra ... With just one musician, you can really do an unlimited number of things on the inside of the piano if you have at your disposal an exploded keyboard”.
Other composers, arrangers, performers, and compositions
Ferrante & Teicher were an American piano duo who produced over a hundred albums of light classical and popular "easy listening" in their long careers (1947–1992). Between 1950 and 1980 they included partially prepared pianos on a number of their tunes to add percussive effects.
On his 1968 album Blues Roots, Dave Brubeck prepared a piano by laying copper strips across the strings to give the song "Blues Roots" a honky-tonk sound.
Denman Maroney performs on what he has dubbed 'hyperpiano', which "involves stopping, sliding, bowing, plucking, striking and strumming the strings with copper bars, aluminum bowls, rubber blocks, plastic boxes and other household objects."
Cor Fuhler pioneered many inside piano techniques during the 1980s and recorded his first prepared piano solo album 7CC IN IO on GeestGronden in 1995; recorded The Hands of Caravaggio with John Tilbury and M.I.M.E.O. on the USA label Erstwhile Records; and in 2007 he released Stengam on the French label Potlatch.
Since 1982, Roger Miller has developed his own take on prepared piano in his work, initially on Mission of Burma's single "Trem II". Miller has since released many albums (on labels including Ace of Hearts, SST, New Alliance, Atavistic and Matador) incorporating this technique. His concert hall compositions since 2009 have often utilized prepared piano.
The strings' original pitches remain perceptible; and
The preparation is not fully reversible.
Although the tacks can be removed from the hammers, inserting them causes permanent damage to the felt; for this and other reasons, the use of tacks is generally discouraged by piano technicians.
The Acoustisizer is an electroacoustic musical instrument built from a small grand piano with built-in speakers, magnetic guitar pickups, PZMs, and prepared piano strings. It was built as part of a graduate thesis project at California State University Dominguez Hills by Bob Fenger (1983), a student of Richard Bunger (author of the Well Prepared Piano). Speakers are built into the bottom of the instrument, redirecting its own amplified sound back onto the sounding board, with strings and magnetic pickups creating an amplitude intensity loop, which in turn drives and vibrates suspended kinetic oscillators (assemblages of vibration sensitive materials). Secondary control parameters allow extraction of vibration and sound phenomena from the kinetic oscillators through a series of proximity microphones and PZMs (piezo-electric contact mics). An article by the inventor was published in Experimental Musical Instruments Magazine April 1991, Nicasio CA. It includes pictures of the kinetic oscillators and stages of the construction process, including an underbody view of the speaker system configuration.
^Bunger, Richard (1973). The Well-Prepared Piano. Colorado Springs: Colorado College Music Press
^Pasler, Jann (2000). "Race, Orientalism, and Distinction in the Wake of the 'Yellow Peril'." In Western Music and Its Others: Difference, Representation, and Appropriation in Music, ed. Georgina Born and David Hesmondhalgh. Berkeley, Los Angeles, and London: University of California Press, p. 107.
^Bartók, Peter, Moses Asch, Marian Distler, and Sidney Cowell; revised by Sorrel Hays (1993 ). Liner notes to Henry Cowell: Piano Music (Smithsonian Folkways 40801). p. 12 (unpaginated)
^ Nicholls, David (1991 ). American Experimental Music 1890–1940. Cambridge, New York, and Melbourne: Cambridge University Press. (p. 523) ISBN0-521-42464-X