Watch the The Soft Palate online guitar lesson by Karan Andrea from Guitar Player Wanted: Vocals A Plus
Your soft palate is just behind the hard palate. You can feel it if you run your tongue back over the roof of your mouth. Where the hard portion ends, the soft palate begins, and the uvula (which looks like a little speed bag) is at the end of your soft palate.
Your soft palate does move, and you can learn how to raise and lower it voluntarily. This is important, particularly as you sing higher in your range. If you don't raise your soft palate, you can sound flat, even if the notes you are singing are on pitch as they leave your cords. This happens when the soft palate is in the way and affects the timbre of your voice. Another unpleasant effect of not raising that soft palate, is that it can place the sound directly into your nose, and make your tone sound very pinched and nasally. Once you understand the motion and the muscles involved, practice raising your soft palate until you can control its movement both up and down. This won't take too long, but these very small movements give you huge results.
Get in the habit of raising your palate and dropping your jaw simultaneously as you sing higher and higher in your exercises. This will give the tone more space to resonate in. Think about how sound bounces so beautifully in the vaulted ceiling of a cathedral. You are creating that same sort of space in miniature just by dropping your jaw and raising your palate. Remember that its effect on your tone and timbre is quite radical.