street piano

noun2

1. •
   A piano placed in a public area to encourage passers-by to stop and play.
2. •
   (historical) A mechanical piano used by street entertainers, operated with a crank that turned a wooden cylinder from which leather hammers were thrown against the strings.

   • I keep my countenance, / I remain self-possessed / Except when a street piano, mechanical and tired / Reiterates some worn-out common song […] — 1916