This is an entry from my blog.
Singing isn't just about staying on pitch, proper breathing, etc. Believe it or not, the way we pronounce and enunciate syllables can have a huge impact on the way we sound singing.
It's as simple as this: whatever shapes you make with your mouth muscles, tongue, and teeth will determine not only what comes out, but how it comes out. Making these adjustments drastically changes a person's performance.
I once had a student who had a VERY strong and loud voice. But she tended to go off pitch. We did exercises to get her to use the muscles in her face and mouth working to reshape these notes as they came out. Believe it or not, this corrected her pitch. It was as if someone took a knob and tuned it properly with her moving her muscles in this new way.
I teach that it's much more than the vocals themselves. There's much more surrounding them that can make or break the sound. Of course I teach in such a way that it always sounds great.