That's a real shame about that guy not enjoying somebody else's performance. I just like to be part of the musical texture. Just being part of a group making good music a cappella is incredibly satisfying. (And you don't have to take any instruments).   And it's particularly wonderful when you use no sheet music. When we used to sing madrigals a lot, and had quite a few memorized, I found that as long as I could sometimes get cues from other voices coming in where they're supposed to, we could sing a lot of songs that way.

And it was a real kick.