This lore can be found by a Warrior on Voss.
For centuries, the Emperor’s Voice has delivered the Sith leader’s commandments to his servants. In fact, to converse with the Emperor’s Voice is to have an audience with the Emperor himself, whose power and consciousness have been placed within the Voice’s body. Although the audible voice never changes, the physical individual who does the speaking has assumed many forms–various accounts describe the Emperor’s Voice as anyone from a young human female to an elderly full-blooded Sith male. Regardless of physical appearance, however, the Emperor’s Voice can always be identified by its emotionless, precise and controlled manner of speaking. Some have privately described conversations with this entity as extremely disturbing; there is often the sense that the Emperor’s Voice is listening to another conversation even when he or she is speaking.