Reverb and even Verb are used to describe the reflections that occur in natural environments. A great example how ever cliche it may be would be a person shouting “Hello” into a cave and here’s the echoes from the word shouted “hello-o-o-o” yes its a crude example but you surely know what i mean. Why does this happen you ask, when a sound is produced (e.g your voice) the resulting changes in air pressure emanate out in all directions but only a proportion of this reaches our ears directly. what happens to the rest? well they rebound off nearby or in some cases not so near surfaces such as walls, ceilings etc taking that much longer to reach our ears. in most cases the distance of surface is proportionate to time it takes for the sound to reach our ears. Ok so these reflections will create a series of discrete echoes that all closely compacted together giving the listener info about the surroundings, small, medium, large etc. These reflections are absorbed by the surface they reflect on each time absorbing some of the sounds energy and in hand reducing its amplitude. Also different surfaces have different and individual frequency responses, basically different materials will absorb different frequencies from the sounds energy but i will not be getting into the subject as this is a 101.
Size of area:
Well say you where in a large warehouse and shouted “HELP”, it would take longer for the reverberations to decay away than it would if you where in a smaller area. Now concentrate here, the further away from a sound you are, the more the reverberations would be until eventually (depending on correct conditions and distance of sound) you would just hear a series of distinct echoes rather than an immediate reverb effect (you must of seen films where people shout into the grand canyon). I will say however every one has experienced Reverb! It is such a natural occurrence in every day life that if it where to be removed it can cause an unsettling feeling in certain individuals. The blindfold test, if you where to be Blindfolded you would almost certainly be able to tell what type of room you are in and roughly imagine how big all because your brain interpreting times and frequencies of the area around you as every material has it characteristic frequency resonance and size has it’s certain echo if you will.
The Reverb Unit/Plug:
Now when you have the unit in front of you, you will usually have the following controls
Ratio/Mix or Dry/Wet:
Dry= unaffected original signal
Wet=The actual reverb caused by the signal
this is presented in lots of different ways but all give the same effect, they can be individual controls for wet(volume of actual reverb) and Dry(volume of actual signal) or in 1 control offering a ratio of Dry/wet mix, here the more you turn the control to the desired effect the more that effect will be heard in comparison the the effect you are moving away from.
Pre-Delay time:
this control changes the time taken for the start of the unaffected signal to the start of the first reflection, good for when sounds have a long attack so you can give the sound time to develop before the reverb kicks in so as to not overlap the 2 and cause a muddy mix.
Early Reflections:
Ok this controls how the first few reflections are heard, because it usually isn’t just one surface reflections occur on we receive slightly different sounding ones from each surface, an early reflection control will allow for this altering each early reflection in accordance.
Diffusion:
This is related to the early reflections control, diffusion will measure how far the early reflections are spread across the stereo image. The amount of stereo image depends on how far away the sound source is.
Further away: much of the stereo image will dissipate
Up front: more reverberation but the stereo image will be closer almost seeming monophonic
Density:
After the early reflections comes the remainder, this is referred to as the density. So on the unit this will control the number and speed at which the reflections occur.
Reverb Decay Time:
The reverb decay time is the time it takes for the reverb to decay away or simply fade out. In larger spaces this will usually take longer than in more confined areas. i do how ever use this control with caution as it can really muddy certain sounds in a wash of different frequencies from previous notes if there is too much decay.
HF & LF Damping:
As the abbreviations suggest this will adjust the amount of High Frequency & Low Frequency respectively.
we have these controls because the further reflections have to travel the less high frequency content they might have as the medium they will be traveling through (air) will absorb them and so will soft furnishings. so by reducing HF and the decay time we can give the listener the impression that the sound is in a small area or in my padded cell:-) Now by increasing the decay time and removing select amounts of HF you give the sound source the image of being further away. Now at the other end of the chart by increasing the LF damping you will make the sound source appear as if in a large open space.
Every reverb will have it’s own version of these controls under different names or even the same so always get used to the manual or guide accompanied with it.
This is where the reverb will digitally simulate the reverberation of a space, using the convolution method. It uses pre recorded audio samples called Impulse Responses or IR’s for short. These samples are recordings of the impulse response from the spaces being imitated by the reverb. I wont go into this process in any great detail as i really couldn’t do it justice.
When you’re just starting out with Reverbs your best bet is to stick with the plugin presets. Take a listen to what the presets are doing and get a feel for it yourself. As you get more experienced you may start tweaking the presets to get exactly the sound you’re looking for.
