The better to feel the music, my dear.

to not see what’s goin on but to get into their soul, not the surroundings.

It’s about singing with emotion

nervousness maybe?

Focusing on what they are doing.

I close my eyes when I play the saxophone. It helps me focus on the music.

The soul goes through something while singing that distractions that we can see distract us from. And that thing the soul goes through is pretty amazing.

I close my eyes when I listen sometimes. When I’m not driving! I think that it enhances the experience by removing a sensory distraction.

Focus, totally, as was said.

I think it helps them focus or they are wincing in pain ;)

Yup, focus is really needed. So that you can feel the song better.

I close my eyes when I’m singing because if I’m distracted by something, I forget the words.

I’ve heard mixed results with this one. My vocal professor in college prefers a singer to have his or her eyes open and maintain audience control in that manner. Sometimes though, I think the audience wants to see a musician who is totally vibin’ off their own piece of art!