is this seriously in question?!
I think the original question is not if a person CAN sing and rap. But rather, if a person is rapping, is that simultaneously considered signing?
singing is singing
rapping is rapping
speaking is speaking
Someone earlier postulated that all sounds from the human mouth have tone and pitch, therefore rapping is singing. Well, by that definition, not only are rappers singers, but EVERY person who has ever uttered even a single word is a singer. Not only that, but everyday conversation is song. I'm sorry, but that's crap. There is more to singing than simply creating a sonic frequency. Dog farts have tone and pitch, but would you care to argue that my dog's ass is singing?
I'm sorry, but singing and rapping are definately mutually exclusive. But this doesn't mean one is better than the other. They are simply different. Much like dogs are not cats. Not because dogs are better...but simply because they are different.
The simple fact that there is a term called "rap" indicates that the the music creates a distinguishable difference from your garden variety singer. Yes, Lauren Hill can rap. Yes, she can also sing. She is a singer AND a rapper. But, she is NOT a singer BECAUSE she is a rapper. Nor is she a rapper because she is a singer. The fact that you notice a difference in the vocal style, MEANS THAT THEY'RE DIFFERENT!!! If they were the same, you wouldn't notice when she switched back and forth. You wouldn't categorize her singing as singing and her rapping as rapping.
I don't hear anyone arguing that singing is rapping.