Our hearing mechanism is very good in ignoring redundant sounds and parsing complex auditory scenes. This is a subject that has been extensively studied, but most of the work is in the heuristic level thus impractical for machine implementation. By redefining listening theories in a more rigorous and mathematical framework we can come closer to constructing machines capable of auditory consciousness. When successful, we can apply these principles to engineering problems to obtain significant results, one such application has been source separation.