This column provides background science information for elementary teachers. When the author was young he used to think that the ideal design for a concert hall would contain walls that were composed of sound-absorbing material, like foam or egg cartons or such. He noticed, though, that this was not the case. Most concert halls contain curtains that will absorb sound, but the walls and other surfaces tend to have lots of different angles to them and surfaces that jut out from the walls. Turns out that is not just for visual aesthetics. To understand why concert halls are built the way they are, a way to produce a constant tone that comes out of two different speakers is needed. The easy way to do that is connect a pair of speakers to the computer and download a "tone generator" program from the internet. This article discusses why walls and other surfaces of a concert hall are angled so that the best sound can be produced.