中文：音频
This content type label refers to all of the requirements related to audio for the following checkpoints: 2.5, 2.6, 3.2, 4.4, 4.5, 4.7, and 4.8. When this label is part of a conformance profile, the user agent must implement at least one audio format. Furthermore, when this label is part of a profile, the user agent must satisfy the requirements of checkpoints 3.2 and 4.7 for all implemented audio formats, not just those identified in a conformance profile. The audio requirements apply to audio content that is recognized as distinct and that, according to the encoding format, may be rendered as a coherent unit.
In this document, the term "audio" refers to content that encodes prerecorded sound.An audio-only presentation is content consisting exclusively of one or more audio tracks presented concurrently or in series. Examples of an audio-only presentation include a musical performance, a radio-style news broadcast, and a narration.An audio object is content rendered as sound through an audio viewport. An audio track is an audio object that is intended as a whole or partial presentation. An audio track may, but is not required to, correspond to a single audio channel (left or right audio channel).An audio description (called an "auditory description" in the Web Content Accessibility Guidelines 1.0 [WCAG10]) is either a prerecorded human voice or a synthesized voice (recorded or generated dynamically) describing the key visual elements of a movie or other animation. The audio description is synchronized with (and possibly included as part of) the audio track of the presentation, usually during natural pauses in the audio track. Audio descriptions include information about actions, body language, graphics, and scene changes.