I saw this several times in different movies, but I don't understand what is this supposed to mean. The main idea is when the scene is about to change, for one second or so we still see the picture from the old scene, but the sound is already coming from from the upcoming scene. Why do they do this? What's the purpose of this technique?

  • Just a wild guess: Make the scene change less abrupt.
    – celtschk
    Apr 12, 2014 at 20:16
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    @celtschk Or the contrary of surprising/confusing you with a new sound you can't immediately relate to the scene.
    – Napoleon Wilson
    Apr 12, 2014 at 20:21
  • @Napoleon Wilson, yes, often it is a surprise. When the old scene comes to its logical end there's silence both sound-wise and event-wise (if I can put it this way), and all of the sudden you hear something unexpected, but you still the the old picture.
    – Max
    Apr 12, 2014 at 20:30
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    The technical term is L cut or Split Edit
    – Oliver_C
    Apr 12, 2014 at 20:58

3 Answers 3


Cameron Christopher has a nice short article on the technique at Vimeo; J-Cuts & L-Cuts.

In short one have J-Cut and L-Cut

  • J-Cut aka audio advance, audio starts before video.
  • L-Cut aka video advance, video starts before audio.

It can advance the story in itself by moving the viewer ahead. It also can give a smoother transition, or many other effects.

Find the two examples in the article by Chrisopher to be nice examples.

For example in second video, the packing of the cigarette packet is smoothed out by the J-Cut, rather nicely.

  • 1
    My favorite example is about 37 and a half minutes into the movie Fight Club. It's when [narrator/Jack/not-Tyler] tosses a couple reports onto his desk towards his Cornflower Blue boss and you hear a splashing sound. A few seconds later it cuts to the bathroom scene where they describe who'd they fight if they could pick anyone. It's an amazing moment of Cognitive Dissonance that is perfect for the subject matter of the movie. A great example that doesn't need to be its own answer. Apr 12, 2014 at 23:02
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    Plus I'd add it's a convenient trick for dubbing when translations are significantly longer and/or can't be made 100% lip sync "in time".
    – Mario
    Apr 14, 2014 at 22:04

Nonsimultaneous Sound is something David Bordwell defined it as.

Nonsimultaneous sound is essentially sound that takes place earlier in the story than the current image. This type of sound can give us information about the story without us actually seeing these events taking place.


It's a throwback to the times of movie film projectors. A strip of cellulose would be pulled across a bright light, and then projected onto the screen.

The sound would be from a "sound track", parallel to the image, on the side of the cellulose strip, which would go across a (much) smaller beam of light into a light detector, which would modulate an electric current which would become the sound.

Since the projection beam would be on one part of the projector, and the sound converter on another part, they would be separated in time -- but this separation would be easily compensated for when the film was processed.

The problem comes when two bits of film would be spliced together -- at one point, the projection beam would be shining through one piece while the sound beam would be going through the other. Therefore, the audio would advance to the next scene before the video.

While there is no reason to do so today, some directors like the effect and so do it anyway. Kind of like shooting in black and white or silently to create an atypical result.

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