Using electromagnetic 

solenoids to inductively drive steel strings

The yellow bars on the back of the piano are magnets wrapped in copper wire (solenoids).  An electrical signal generated from any source can be used to mechanically drive the steel strings of the piano.

 

Sawtooth waveforms - which normally sound quite annoying - sound more like a pipe organ when inductively played through the piano.

Electronically triggered music played into the piano strings

 

Midi-triggered signals coming from keyboard sent to computer, processed via SuperCollider to trigger programmed waveforms. Computer sends then out electrical signals into inductive solenoids behind the piano strings to magnetically drive steel strings.