With the cold weather season driving us indoors, it’s a good time to consider how room acoustics affect our sonic space.
You might have noticed that music outside doesn’t sound as good as inside — it’s because of the lack of reflections. Sound bounces off of walls, ceilings, and floors; every room is an echo chamber. Reflections make the music sound louder and fuller, but they can get out of control, piling up and overemphasizing certain frequencies, making speech unintelligible, and music noisy, muddy or boomy.
It happens when there are hard surfaces facing each other; the echoes repeat themselves at a specific frequency. This is called “flutter echo” and it can be fixed by absorption: hanging acoustic panels or laying a rug under a flat ceiling. But too much of that will make a room sound dead. The other fix is diffusion — breaking the largest reflections by, say, putting a bookshelf opposite a bare wall. That’s why you’ll see lots of random surfaces in a good concert hall.
Music: Brian Eno, “Third Uncle,” Taking Tiger Mountain (By Strategy), 1974.
Usually it’s only hi-fi geeks who think about room acoustics, but bad sound is a hazard, affecting concentration, productivity and blood pressure. Acoustical engineers make their living solving these problems, and I really wish they were consulted more often in the design of public spaces — some local restaurants really make it hard to carry a conversation.
But even a do-it-yourselfer with just a little awareness can do much toward freeing us from the tyranny of concrete, tile, and 90-degree angles.