Why is sound so important to film?

Sound is said to be "50% of a movie", it is used to establish and set tone and atmosphere which helps gives the audiences clues to the plot or genre. Sound in film is also used to create realism within the viewer and help extend that "suspended belief".  Sound techniques are often used to convey a certain mood of the film and manipulates the audiences reaction. This mainly applies to horror and thriller films which both seek to represent fear. Most horror films use the classic screaming sound when something jumps out from the screen to attempt to scare you.  This is a worthy moment which makes a horror movie a success.

Foley sounds are often used to glorify or engage the audience more into a film. It is not the actual sound that has been used in the production. Most sound effects such as punches, gunshots etc are recreated and later added in by sound editorial.