What is the nature of Siddhartha's inward voice ?

In Part II, Siddhartha no longer believes that this world hides a more true one behind it. Siddhartha's goal from now on is to discover his place in this world, which requires his experiencing all aspects of it. The contemplative and ascetic lives robbed him of this totality. He will no longer privilege any aspect of his being, thought or senses; he will only listen to the prompting of his inner voice. Just what this voice is and where it comes from is not clear. Was it always really there, just hidden? Does its interiority mean it is a distinct aspect of the Self from thoughts or senses? If it is, is it of this world, like thoughts and senses, or is it somewhere else, hidden? There seems to be no simple answer to these questions. Siddhartha simply acquiesces to its will, granting it an authority which is not justified except with the facile justification that it is himself. But since the nature of Self is precisely at issue, this seems an unsatisfactory answer.