A silent piano is an acoustic piano where there is an option to silence the strings by means of an interposing hammer bar. A silent piano is designed for private silent practice.  In the silent mode, sensors pick up the piano key movement. Older models used mechanical sensors which affected the touch and produced a clicking sound, whereas newer models use optical sensors which do not affect the feel or sound of the piano. The key movement is then converted to a MIDI signal and can link to a sound module, allowing the person to utilize headphones. The pianos also have full MIDI capability and can be linked to a computer for use with notation software, etc.
In all silent systems, engaging the silent function causes a bar to move into place such that it intercepts the shank and stops the hammer from hitting the piano string.
In more advanced systems, usually on grand pianos, the piano's action is also altered when the silent function is engaged. This changes the action's setoff setting so that the escapement trips at a lower point in the hammer's motion towards the string. This allows the action to be regulated correctly in the non-silent setting. Without it the action must be regulated to be a compromise between what is needed in non-silent mode and what is needed in silent mode.
Silent pianos are available from many manufacturers, including Steinway, Bechstein, Bösendorfer, Grotrian-Steinweg, Kawai, Yamaha, Schimmel and Seiler. PianoDisc provides systems to be installed ex post.
- Crombie 1995:94.