I absolutely love this games soundtrack it is absolutely phenomenal and arguably the best soundtrack in all of gaming. I recommend giving it a listen along with the DLC soundtracks! (And play the game too)
Base Game:
(Personal favorite is 'The Raindrop that Fell to the Sky')
DLC 1, Survivors of the Void:
(Personal favorite is 'A Boat Made from a Sheet of Newspaper')
DLC 2, Seekers of the Storm:
(Personal favorite is 'Yane No Mori')