Musical Space 11/15: Acoustic

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KMUW / Mark Foley

This week on Musical Space, beware the standing waves.

Acoustic

The acoustics of a room can really affect you. Good acoustics can be just as aesthetically important as a good color scheme. Bad acoustics can make it impossible to listen to music or carry on a conversation.

Acoustics are mostly about reverberation - how sound bounces off of walls and other surfaces. A room with a lot of reverberation is described as “wet” - the echos build, adding richness to the sound. That’s why its fun to sing in the shower. Too much, though, makes the sound unintelligible and fatiguing. A “dry” room is the opposite - there is a lot of sonic clarity but it can sound sterile and unexciting. A wet room favors vowels, a dry room favors consonants,

Reverberation can be controlled somewhat by the type of surface. Carpet absorbs, concrete reflects, wood is a great compromise between the two.

Some kinds of reverberation can be better than others. Sound will bounce repeatedly between parallel walls at a certain rate, which means some pitches will be favored more than others. These muddy-sounding echos are called “standing waves,” and unfortunately our preference for 90-degree angles means we experience a lot of them. Its also best to have the length, width and height of a room to not be the same, so that the standing waves don’t coincide. Concave walls are also bad because they focus the sound unnaturally.

The worst acoustics I have ever experienced are probably those of a racquetball court - a nearly perfect cube of concrete. A close second would be an indoor pool, with the sound bouncing between the water surface and a flat ceiling. Now you have an idea why a hockey arena is not the best place to hear a concert.