Sound - diegetic sound

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 film's world Diegetic 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
This is a sound which the characters within a film/footage can hear. Diegetic sound can include everything from traffic noise, telephone rings. doors slamming and animal sounds, to industrial machinery and dialogue These sounds may be used to generate a reality effect for the audience, but can also take on symbolic meaning.

For example: The perpetual rain of the metropolis in David Fincher's film "Seven" creates a constant backdrop to the action of the film. it also becomes representative of the inhospitable nature of the city.

Diegetic sounds can also become synonymous with particular characters and act to signal their particular presence in a film. In the film "Scream", for example, the killer harass their victim with the use of a telephone. The opening image of the film is of a phone ringing and the character who answers it becomes the first victim. From then on in the film, the sound of a phone ringing becomes associated with the disjointed voice of the killer contacting their next victim. This everyday and banal sound then becomes threatening and creates tension for the audience.