John Cage's Sonatas and Interludes revolve around the principle of "prepared piano". This concept, coined by the American composer, is to hinder the piano through various objects (screws, rubber and other elastic) placed in its crate and also between his strings. The purpose of this device? Changing the usual sound of the piano to disrupt the sense of the listener and lead to different listening, emotional outcome of direct experience.
JOHN CAGE : Sonata and Interlude