A violin produces sound through the vibration of its strings, which occurs when the player draws the bow over the strings and sets them in motion. From there, the bridge of the violin transmits those vibrations to the back and front plate of the instrument, causing the entire body of the violin to serve as a resonating chamber and amplifying the sound produced.
The components of the violin are carefully designed to transmit sound waves that lie in the heart of the human hearing range. The bridge connects to two structures inside the violin: the sound post and the bass bar. The sound post goes all the way through the instrument, and it transmits treble notes to the relatively stiff back plate of the violin. The bass post helps transmit bass notes to the more flexible front plate, allowing it to amplify the lower frequencies when played.
To produce a note, the player first uses the off hand to restrict the length of the strings that vibrate. By pinning the strings to the neck at various places, he can adjust the note produced by any one string. Then, the player draws the bow across the string or strings, altering the speed and force to adjust the loudness and characteristics of the notes. From there, the construction of the violin takes over, amplifying and shaping the sound for the audience.