diegetic/non-diegetic sound

Diegetic sound:

Diegetic sound is Sound whose source is visible on the screen or whose source is implied to be present by the action of the film: 

voices of characters 

sounds made by objects in the story 

music represented as coming from instruments in the story space ( source music)

Diegetic sound is any sound presented as originated from source within the scene. 

 in class we discussed the differences and the effect of each. diegetic can be emphasised by editing in post production so a certain action is clear to the audience like the loading of a gun or the pressing of a lift button. this will show the audience that a character has done something to a certain significance. and also to draw attention to a object or movement to show importance 

non diegetic:

Sound whose source is neither visible on the screen nor has been implied to be present in the action: 

narrator's commentary

sound effects which is added for the dramatic effect

mood music

Non-diegetic sound is represented as coming from the a source outside story space. 

The distinction between diegetic or non-diegetic sound depends on our understanding of the conventions of film viewing and listening.  We know of that certain sounds are represented as coming from the story world, while others are  represented as coming from outside the space of the story events.  A play with diegetic and non-diegetic conventions can be used to create ambiguity, or to surprise the audience. this can also create an atmosphere in the scene as fast pace music or sounds will give the effect of excitement