Planning - Sound

In films, there are three types of sound applied to feature films, diagetic, non-diagetic and sound ambiguity.

Diagetic sound is sound within a film that the characters themselves can hear, and a sound they acknowledge in the film. For example, hearing the ring of a doorbell and the character goes to open the door due to the sound of the doorbell. 

The opposite of diagetic sound is non-diagetic sound. Non-diagetic sound is sound that the characters in the film do not notice or know is present. Non-diagetic sound is used to add atmosphere and add to the ambiance of a scene. An example of non-diagetic sound is the use of a background song in a scene, such as displayed in the opening sequence of Matrix Reloaded.

However, sometimes sound in films can transition for non-diagetic to diagetic, and so causing sound ambiguity. This is used to create an effect of the audience watching or listening in on the characters, and getting the impression the characters are unaware of the sound, then to realise that they are aware of it. An example of this is shown in the opening sequence of 10 Things I Hate About You.