tones when singing a chinese song?
Simple answer:

Sinosplice

Tones In Chinese Songs


  I’ve been asked a number of times: if Mandarin Chinese is a tonal language, what happens when you sing in Mandarin? Well, the answer is the melody takes over and the tones are ignored. Pretty simple.


A graphic representation of tones spoken vs. sung in Mandarin [also from Sinosplice]:


  


Sometimes, though I think, if you listen closely a lot of people are included to sing the tone even though they don't need to.