‘Sync’, short for syncronization, refers to audio and video (recorded separately) being connected in time, matching each other perfectly.

Conventions such as a 2 pop (a small 1kHz blip 2 seconds before a film) and a tail pop (the same thing 2 seconds after a film) as well as time-code, help editors sync audio to video.

Out of sync audio can occur due to frame-rate or sample rate differences, or incorrect editing. It is important that the video monitor which a sound designer uses is properly synced with delay compensation.

screenshot of 2 audio sources on a timeline, out of sync
image courtesy of
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