What is the difference between non-synchronous (or asynchronous) and non-simultaneous sound? Basically, the difference is about sound that takes place in a different time to the action (such as a sonic flashback) which is non-simultaneous, and sound that is not synchronized with the action on the screen (asynchronous). Non-simultaneous sound would include sonic flashbacks (“Luke, I am your father”) and asynchronous would include satellite delays at live events and bad dubbing in old martial arts films.
What is the difference between non-diegetic and internal diegetic sound? Non-diegetic sound refers to any sound not audible to characters in the world of the film whereas internal diegetic sound forms part of the story world but is not audible to all characters. Non-diegetic example would be the musical score. Internal diegetic sound refers to a character’s thoughts.
For more sound terms see FilmSound.org. You may also find these Wiki articles on Diegesis and Cinematic techniques quite useful here – great for a quick understanding of terms, but NOT to be cited in academic essays.
DIEGETIC: Spider-Man – the song ‘what we’re all about’ is played in the scene where Uncle Ben drops Pete off just before he is killed. Although the audience can hear it is supposed to be on the car radio.
NON-DIEGETIC: JAWS – although the music is heavily connected to JAWS the music that plays before the shark attacks is only heard by the audience watching the film and not by the characters the shark is about to attack.