Homer- Homer can't really sing. When we hear him we all shudder. Simon would probably tell him to just shut up. Paula would probably go something like that he is way off key or is just foolish. Randy would just stare and say he sucks. 
Homer Yay or Nay- Nay 

Bart- We've heard Bart sing a few times. He is fairly good. Simon might just say your in, but also might add in you need a little work. Paula would say I loved it. Randy would probably just agree with the two and say your in. 
Bart Yay or Nay- Yay 

Apu- Apu was fairly good when singing 'Who Needs the Kwik-E-Mart?' so he might have a chance. Simon would probably just say get rid of the clothes but probably would put him in. Paula would say that your wonderful and loved the song. Randy would say that he is good 'dawg' and welcome him in. 
Apu Yay or Nay- Yay 

Sideshow Bob- If I remember correctly Bob sang twice. He is a good singer and I think that all three would accept him in. Simon would just probably lose the psycho/maniac thing. Paula would say that she adores his singing. Randy would say 'dawg' so many times Bob would lose his mind, and then welcome him. 
Bob Yay or Nay- Yay 

That is about all the people I could think off the top of my head. We had 3 Yays and 1 Nay. If you can think of anymore people that sang a solo e-mail me at tbob@roundspringfield.com and tell me who and what song. That about does it. I'm Jared Munson and your not. Good-bye.