The Term "Closed captions"
A text version of the words spoken in a video in addition to a description of the environment or an action that are relevant to a video. For example, “Go to class, is heard over the PA”, “The car backfires” and “rain hits the roof”. A closed caption file usually includes a timestamp alongside the text to indicate when the text will appear in the video. Common closed caption file formats are SRT and VTT.