Small audio files can be embedded directly within TiddlyWiki. Embedding isn't suitable for large files (over a few hundred kilobytes) because it increases the size of the TiddlyWiki file.
For example, the tiddler [[TiddlyWiki.mp3]] contains an MP3 recording of the word "TiddlyWiki". If you visit that tiddler, you should see an audio player that will play back the recording.
External audio tiddlers use the ''_canonical_uri'' field to point to an external audio file/stream, and have their ''text'' field blocked. This reduces their size considerably, but still allows for playback.