Use of Sound in Film

'Breaking the fourth wall' - introduced by philosopher Denis Diderot - is when a character acknowledges the audience either through speech or looks. Movies which do this are known as meta-fiction movies. As well as movies, television programs also do this, as can be seen in Miranda. 
Breaking the fourth wall is effective as it drags the audience further into the film or program as they feel like a part of it due to them being addressed by certain characters.

Narrative can also be considered a use of sound. Narration is used to add more detail to the story of the film. Examples of these can be seen in earlier posts through the examples of "Dinosaur" and "Kick-Ass".
Narrative is used to help the audience understand the storyline and feelings of characters more. 

Diagetic sound - sound which both the audience and those in the film can hear - can be useful in film as it makes the audience feel more as if they're in the film. In a stereotypical horror film, diagetic sounds would include screams and creaking.

The opposite of diagetic sounds are non-diagetic sounds. These are sounds of which only the audience can hear, these often come in the form of music. Non-diagetic sounds are used to create certain feelings and tensions to help the audience connect with the film.

Sound in film also helps us to predict what is going to happen during the film. For example, if we hear a knocking on the door we can expect to meet a new character. 

The final use of sound I will address is silence. If a film becomes unexpectedly silent it creates a certain tension in which the audience anticipates the next action. Silence is as effective as sounds as it makes the viewers feel a sense of uncertainty.