Why this class is so great

I'm sitting here in one of my classes, and we've set up standing waves in the room so that you can walk around the room and hear really loud and suddenly the sound goes away. But then while walking around you stop in a node and the sound is gone. But then when in a node and someone is talking out of a node, their voice is choppy. Then we did kilohertz of sound and at 17 it killed a couple people in the room but I couldn't hear it, not until the 15-16 did I hear it. I then asked why it was killing some people at 17 but I couldn't even hear it, and my teacher asked me how many concerts I've been to which I replied with "about 20" and he said, there's your answer. :) What weird stuff.