These options control the various sounds in the game. They all seem to take effect immediately, no restart required.
The volume of the background music in game.
Event Music Volume
Controls the volume of music played during special events, such as a notice of a quest.
Controls the volume of environmental sounds like wind, birds chirping and so on.
Sets the volume of all non-music sound in the game.
If turned off, all sound effects are disabled.
If turned off, all background music is disabled.
Enable Event Music
If turned off, no special event music plays.
Enable Ambient Sound
If turned off, disables background sounds.
Default: Stereo Speakers
Sets how many speakers Elemental uses for rendering sound. You should change this to match your setting in Windows unless it causes a problem.