Research: The Importance Of Sound In Horror Films

Sound is used in many different ways within a film to create a feeling (an emotional response)
there are two types of sound that are used:
Diegetic sound is Sound which the source is visible on the screen or the 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 film's world 
Digetic sound can be either on screen or off screen depending on whatever its source is within the frame or outside the frame. 
Another term for diegetic sound is actual sound 




Non-diagetic sound is Sound which the 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 (horror), or to surprise the audience (comedy). 
Another term for non-diegetic sound is commentary sound. 


Here is an example of how both types of sound is used:


In this scene we can start to see how much impact sound has on a film. Without music the scene seems much more easy going, whereas when the music is added it creates tension for the audience and makes them sit on the edge of their seat. The tempo is very upbeat and fast which creates a feeling of fear and danger.