Sound

Sound is a key element in any successful modern film. 

There are two types of sound that the audience will notice in almost every film they watch. This is diegetic and non-diegetic sound.

Diegetic sound refers to sound that is within the world of the text. This means sound that the characters within the film would be able to hear, for example, if a dog is barking next to a character and the character can hear the dog, that is an example of diegetic sound. Other examples can include music and dialogue. Music is not exclusively an example of diegetic sound however. 

Non-diegetic sound refers to sounds that the audience can hear that the characters within the film cannot, otherwise explained as sound that is outside the world of the text. Common examples include voice overs and soundtracks. 

Another thing to keep in mind when analyzing sound within a film is whether or not the sound is on or off screen. 

''On screen sound'' is a term used to describe sound that can be seen on the screen, whereas off screen sound is the opposite. For example, if two people are having a conversation within a film and they are in focus, that is on screen sound. However, if you hear a police car outside but the focus of the camera is on the inside of the house and no police car can be seen, that is off screen sound. Directors typically use off screen sound to create an effect of suspense, they can also use this technique to save money, if they are able to generate the sound of a police car for the scene they are trying to execute without actually needing to show the police car they save themselves a lot of work.