Singing Blind?

I get to chorus practice. The practice that I was told by my tenor colleague (the twerp) was a concert. The practice in the completely opposite side of the city from our school, in a building nothing to do with school....INJA? Don't know it. What is going on? Oh, it gets better.
So, I get into the building by a sheer stroke of luck, and someone leads me up to the room where my chorus is. And the Sciences Po orchestra (consisting of 8 people...). And there seems to be special needs people in the audience.
"Okay," I think to myself, "So we're having a little show for the special needs people."
Then the special needs people get on the stage with us.
Now I'm confused, and slightly nervous.
My tenor partner isn't there (of course), so I'm all of a sudden surrounded by strange men who are trying to talk to us but I can't understand their slurred French. WHAT is going on?
Through using my slewthing skills, I deduce that these people are mostly blind. And the non-blind ones are their leaders.
And then the blind headmaster starts conducting.....for blind people....and the Sciences Po kids. This is normal, right? For a blind man to be conducting a sea of blind people in music? Because they can see him?
The organist was blind, too.
And it was ridiculous because I sing quietly (since I'm singing low) but the blind men were matching my pitch and following my lyrics. I could tell they were changing words to fit mine!
It was the most flustering 2.5 hours of my life.