Audio (Music / SFX / Voice)

Audio DLC is for added content that doesn't affect the gameplay but change how the game sounds.

Music: DLCs may be something like new songs for players to sing via microphone or to play with a guitar controller. Or, it can be the game soundtrack (not just a soundtrack to listen on it's own, that is not a DLC as it doesn't require a game) which changes the music during gameplay to a new tracks.

SFX: stands for Sound Effects. This can change how some actions sound (for example, user interface sounds or battle sounds or any other sound effects during gameplay).

Voice: DLCs are used to make characters sound different. Either additional or new voice-acting may be added. Adding new languages (voice-acted, not as subtitles) which the game didn't initially supported also falls under this category.

Important!!!

This DLC focuses on audio content exclusively. Adding new map/level, new character, new story content which obviously contains new audio materials doesn't require this genre to be selected, and in fact it shouldn't be.