This small music box can play songs at the request of the holder. As a bonus action, you can command the box to play a song that it knows, causing the contraption to emit a slightly tinny rendition of the musical number at a moderate volume. The box can know up to five songs at a time, and can not recreate lyrics or other creature sounds. It has a small knob on the side that adjusts the box's volume, being as quiet as a whisper to as loud as a scream.
Sheet music can be fed into the box through a narrow slot along the bottom of the device. Sheet music must be labeled with a song title, page number, and instrument in order to be replayed. Pages failing to meet the requirements causes the box to make a sad, trumpeting noise, and are spat back out. Once a sheet is successfully fed into the box, it is consumed and cannot be retrieved.
If the new piece of music will cause the box to forget an older one, it quickly plays several bars of the now-forgotten number before slowing to a stop.
As the beholder fell to the ground, no longer supported by its own unearthly levitation, the last thing it heard was the sound of...karaoke?