I don't know anything about audio processing algorithms, but (assuming there's a way), presumably with enough audio sources, there'd be a commonality between each one that describes the 'correct' sound. I.e. if there's different noise going on in each source (people talking around each microphone, at a gig, intermittently), you don't really need to decide which sound is 'clean' because you'd know which sounds are inconsistent...(?)