While the following stuff is one of those theoretical things, it’s a rather interesting one. If you are into audio, you have probably heard the following description at some point: reverb is to sound what shadow is to visual imaging and perception. It sounds nice and at first glance it might seem to be logical; reverb follows the sounds like shadow follows the objects in our visual world… well, kinda. But think about it again: reverb is able to tell us the position of a sound, from front to back, and thus it’s capable of indicating the distance between us and the sound source. Can a shadow tell us the front to back position of an object? Does it indicate the distance from the observer? Does a shadow follow an object in time? The answer for all of these questions is a no. A shadow shows us the position and strength of the light source, in relation to the object. It’s pretty much irrelevant when we try to translate that phenomenon to the audio world.
Reverb is more like blur, not shadow
So what is reverb like then? Well, it’s more like the blur and (blue) coloration that occurs on objects that appear at a distance from the observer. And while that seems to be a better analogy, it still doesn’t describe the effect that a reverb’s pre-delay has on a sound source. Because reverb doesn’t only tell us the above things (front-to-back position, distance), it also tell us the size and quality of the environment our sound source is in. Also check out acoustic shadow; it’s something entirely different from what reverberation is.
Analogies are lame
Now at that point, we either give up searching for a good analogy from the visual world, or just plainly say, reverb is like all that stuff happening to light and all those things under it… which sounds pretty unsure and pointless.
Zen always helps – or not
Remember what the venerable zen master said between two farts, both of which sounded eerily akin to the word “om”: “We don’t always need analogies.”