Zero Level
This is a standard reference audio level used when discussing relative levels. Commonly the zero level is chosen to be 1 mW. This corresponds to 0.775 volts rms across a 600 Ohm resistance.

Musical instrument composed of strings mounted upon a resonate frame, strings can be plucked with fingers or struck using small mallets.

The drive to create, perform, and reproduce music is so common to all mankind, a drive so basic that when a man cannot find an instrument to suit him, he creates his own.”
Joseph Howard