Users who are deaf, hard of hearing, or having trouble understanding the audio information must be provided with a text based alternative.
Video Content with Audio
Captioning should be provided for the audio portion of a video. The captioning must be synchronized with the audio so that someone reading the captions could also watch the speaker and associate relevant body language with the speech.
Audio-Only Content with No Video
Audio files with no video are not considered multimedia. However, since audio is a non-text element one of the following text-equivalents must be provided for deaf or hearing impaired users.
HTML based transcript
Text transcript
A text or HTML summary