Reverb is a DSP that makes a sound persists for a determined amount of time after the original sound occurs. The persisting sound is like a tail of reflections that tapper off after the original sound is heard. It’s more or less recreating the effect that is heard in a large empty room, and is a common effect that is used for all sorts of applications in music and sound editing.
HISTORY:
Okay, a brief history of reverb for all you history buffs. Back in the analogue days the original method of creating reverb was by building an echo chamber. This room which was typically built for sound studios would be made of different materials to get different sounding reverberations. The recording engineer would place a speaker in the room to play the sound they wanted to add reverb to, and then a microphone would be placed at a distance from the speaker to pick up the sound of the room. Echo chambers are not common at all today, and the term is now mainly used to describe people’s tendency to find news that agrees with their opinions on Facebook.
Barry Blesser designed the first digital reverb unit, the EMT 250, in 1976. It cost a mere $20,000, and approximately only 250 were ever built.
PARAMETERS:
There are different kinds of reverb, which we will go into more detail in future posts. Other reverbs include Plate reverb, Spring reverb, and Convolution reverb.
When using a reverb DSP, you will likely come across a handful of parameters to change the sound to your liking. Not all reverb units have the same parameters, but here are the most common one’s that you’ll likely see:
Size/Decay: This adjusts the size of the room. A larger room will create a longer reverb, while a smaller room will shorten it.
Density: This is the rate at which diffusion builds, or how quickly the reflections add up until they sound like a full washy reverb. On a more technical level, it could be said that density is the point at which all the reflections in a space reach an equal energy. If density is set to a quick time you will get a natural sounding room. However, if set too quickly resonance will occur which creates a metallic sound that’s very unnatural. This is a byproduct of old digital algorithms and is handled far better by newer technology with more advanced algorithms. If density is set to a slow setting then the room will sound very flat with parallel walls.
Damping/Absorption: This setting changes how many high or low frequencies are heard in the reverb. Rooms can be made from different materials that will affect sound waves differently. So, this setting can change the room from sound like it’s walls are made from metal into walls covered in fabric.
Pre-delay: This adjusts how quickly the reverb is heard after the original source sound.