Young Blonde Girl Wearing A Necklace At The Piano

A silent piano is an acoustic piano having an option to silence the strings by means of an interposing hammer bar. They are designed for private silent practice.
The transposing piano was invented in 1801 by Edward Ryley. It has a lever under the keyboard used to move the keyboard relative to the strings so that a pianist can play in a familiar key while the music sounds in a different key.
The prepared piano, encountered in some contemporary art music, is a piano with objects placed inside it to alter its sound, or that has had its mechanism changed in some other way. The scores for music for prepared piano specify the modifications, for example instructing the pianist to insert pieces of rubber, or paper, or metal screws or washers, in between the strings. These either mute the strings or alter their timbre.
Available since the 1980s, digital pianos use digital sampling technology to reproduce the sound of each piano note. Digital pianos can be sophisticated, with features including working pedals, weighted keys, multiple voices, and MIDI interfaces. However, when the damper pedal is depressed on such an instrument, there are no strings to vibrate sympathetically. Physical models of sympathetic vibration are incorporated into the synthesis software of some higher end digital pianos, such as the Yamaha Clavinova series, or the KAWAI MP8 series.