Also called "video description" and "descriptive narration."
+In the context of audio descriptions, synchronized media primarily refers to all audio and video content intended to be played to the same time base, which allows an author to align the timing of the audio descriptions in the audio track with the appearance of the relevant visuals in the video. Intentionally asynchronous sound can take place in the context of time-based, synchronized media. A video that is accompanied only by background music is still "synchronized media".