- a grand piano that has been altered for some modern compositions by having various objects attached to its strings to change the sound and pitch, and performance on which typically involves playing the keys, plucking the strings, slapping the body of the instrument, and slamming the keyboard lid.
- a piano in which some strings have been damped by having objects placed between them or tuned differently from the rest for specific tonal effect. This process was pioneered by John Cage
