Noise Reduction Profile Question

I read the manual and I know that Noise Reduction will use The Whole Show as a Profile if a “formal” Profile is not available. That seems to be counter-productive. You’re asking Noise Reduction to remove the show from itself.

I know from an older posting that Noise Reduction selects sounds that are present for the whole show—likely to be “noise.”

How does it do that? Where is the threshold? If the sound is there for “most” of the show? Over half? Suppose there is a flip-flop interview and the noise is only there for one performer?

There must be a “personality” or decision process.