Listen to this track verse then listen to the chorus part.
There is subtle difference in his vocal tone. I have searched, most people claim that Eminem does not use Auto-tune and he mangles his voice tune purely by his mouth.
Well, that's okay.
It seems the vocal is mangled somehow to emphasize the tonal part of his voice ( I don't know really how to say it - Just listen to the chorus )
How is this contrast achieved?
I guess you guys might have different opinions regarding my question like saying he has just read a different line in chorus with different intonation. I mean no offense to his fans. After all, he is Eminem. Any suggestions to emphasize the tonal part of vocal with any sort of trick so it pops out without ruining balance?
The solution can't be compressing the mid-range and balancing the vocal. Even these multi-band compressors available don't have resolution to emphasize certain frequencies. I might have gotten too technical. I know there exists a good answer.
Let's hear what you guys have to say regarding the question.

 

You can try vocal layering and perfect alignment to create a single voice as a target.
For example recording a clean voice and then adding layers with different characteristics.