Examples of extended techniques include bowing under the bridge of a string instrument or with two different bows, using key clicks on a wind instrument, blowing and overblowing into a wind instrument without a mouthpiece, or inserting objects on top of the strings of a piano.
Twentieth-century exponents of extended techniques include Henry Cowell (use of fists and arms on the keyboard, playing inside the piano), John Cage (prepared piano), and George Crumb. The Kronos Quartet, which has been among the most active ensembles in promoting contemporary American works for string quartet, frequently plays music which stretches the manner in which sound can be drawn out of instruments.
rudimental or "dynamic" double bass on the drum set, using hand rudiments such as double stroke rolls and flam taps and playing them with the feet
stacking 2 or more cymbals one on top of the other to change the sound properties of the instrument
custom-built percussionmallets, occasionally made for vibraphone or tubular bells (and other pitched-percussion in increasingly rare circumstances) which feature more than one mallet-head, and so are capable of producing multiple pitches and difficult chords (though usually only the chords they were designed to play). These mallets are seldom used, and percussionists sometimes make them themselves when they are needed. When implemented, they are usually only used once or twice in an entire work, and are alternated with conventional mallets; usually they are used only when playing a different instrument in each hand.
The Orchestra: A User's Manual by Andrew Hugill with The Philharmonia Orchestra. Includes definitions, descriptions and video interviews of extended techniques for most all common orchestral instruments.
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