Merge pull request #784 from AOMediaCodec/issue_764

Fix #764, channel clarification

index.bs

@@ -303,7 +303,9 @@ The model comprises a number of coded [=Audio Substream=]s and the metadata that
 
 The model includes one or more [=Audio Element=]s, each of which consists of one or more [=Audio Substream=]s. The [=Audio Substream=]s that make up an [=Audio Element=] are grouped into one or more [=Channel Group=]s. The model further includes [=Mix Presentation=]s and [=Parameter Substream=]s.
 
-The term <dfn noexport>3D audio signal</dfn> means a representation of sound that incorporates additional information beyond traditional stereo or surround sound formats such as Ambisonics (Scene-based), Object-based audio and Channel-based audio (e.g., 3.1.2ch or 7.1.4ch).
+The term <dfn noexport>3D audio signal</dfn> means a representation of sound that incorporates additional information beyond traditional stereo or surround sound formats such as Ambisonics (Scene-based audio), Object-based audio and Channel-based audio (e.g., 3.1.2ch or 7.1.4ch).
+
+The term channel means a component of Scene-based audio, a component of Object-based audio, or a component of Channel-based audio. When used in the context of Channel-based audio, it refers to loudspeaker-based channels.
 
 The term <dfn noexport>Immersive Audio</dfn> (IA) means the combination of [=3D audio signal=]s recreating a sound experience close to that of a natural environment.