Until the advent of the sound movie (1936) there were only mimes and title cards to indicate key dialogues, parts of the plot and even some emotions.
During the silent era there was music in the cinemas (usually a live piano player) but sometime it was used more to dull the noise of the projector then to underly what was happening on the screen. At the beginning, the contribution of music to movie art was considered quite marginal, but it did not take a long time since music “has come to be one of the means of story-telling.” (Tiomkin, 1974).
Some music transmits its intrinsic emotions and artistic value even if you listen to it outside of the picture contest; in spite, other music outside of such contest can even be annoying to listen to. Once again Tiomkin suggests: “Just try to transplant any picture’s musical score to similar scenes in another picture.
You will find that the transplantation doesn’t live”. This is the reason why a movie director will make sure to have the right music to sync with his film only once the film is projected in sync with it. Expanded Music Sync with its built-in screen and music players allows you to watch any picture sequence rolling out more and more times along with different music edits, giving you the chance to compare the same sequence with different music online and in real time.