Basic Audio is a free introductory textbook to the basics of audio physics and electronics. See the editorial for more information....


Author: N.H. Crowhurst

Left: loss of background sounds due to excessive absorption - such as in an anechoic room - create a loss of perspective.
Right: sound reflections in a room give a sense of perspective.

Although reverberation makes the endings of sounds less important than their beginnings, this does not mean we can ignore the endings. Human hearing is very conscious of the reverberation even though it may not listen to it so critically.

You notice nothing unnatural about talking in an open field. There is no echo to your voice because the sound of it can keep on going without being reflected. You also notice nothing unnatural about talking in a room where there is a very definite echo, or reverberation, to your voice. But try talking in an anechoic room (a room used for acoustic testing in which walls, floors, and ceiling are made completely absorbant of sound); try one of those padded rooms they use for violent cases in mental institutions (if you ever have the opportunity). Either of these places will give you a quite unnatural sensation of "soundlessness," rather than of silence.

When you are outdoors, it may be quiet but there are little sounds going on that give you a subconscious perspective of where you are: birds singing in summertime or other incidental sounds that are usually "in the background" outdoors. When you are indoors the reverberation of your own voice subconsciously tells you what kind of room you are in. But in the padded cell or anechoic room, because of the excessive absorption that removes all background sound, either from outside or from your own voice, you feel your voice is "lost." There is no background to give you perspective.

Last Update: 2010-11-03