The room where my choir rehearsals are held has a semicircle of chairs in three rows; and the chairs are on wide wooden risers covered with carpeting. They're nice to sit on, but murder for my concentration. We're in the middle of rehearsing some pretty difficult music right now, with strange chords and strange rhythms; and several people tap out the beat with their feet. That's OK, I do it too - only I tap my toes within my shoes, or clench their muscles or something else that's quiet. All these other people tapping their shoes on these hollow wooden risers are driving me insane. They keep going for a measure or two even after the director stops us to go back and try a phrase again, and tonight a few of them started even before the director gave us the tempo, presumably trying to guess what it was going to be. It's really hard for me to concentrate when I hear BANG...BANG...BANG...BANG like marching in my ears.