Below we do a bit of reverb revision and answer some of the most common questions advanced beginner music producers have when it comes to using reverb in music production and mixing.
What is reverb?
Reverb is what people perceive
when sounds in a natural space reflect off surfaces and arrive back at
the ears of people located in the same space. It can be distinguished
from direct sound by the fact that it’s reflected sound.
can think of natural reverb in a room as the way a room reacts to
sounds. This is often called the impulse response of a room.
Here’s how it happens:
Imagine you’re in a room with a single speaker in it.
You play a sound, tone, speech or music through the speaker.
The speaker cone vibrates to create sound waves.
Some of the sound waves travel directly to your ears. These are direct sounds.
All of the direct sounds reflect off surfaces in the room. Some bounce back to your ears. These are reflected sounds.
Reverb is the accumulation and diffusion of all these reflected sounds.
Reverb vs. Echo:
Reverb is technically similar to echo in that both are
created by the delayed return to the listener’s ears of reflected
sounds and their relation to the direct sound in time.
difference is that the amount of time that passes between the direct
sound and the reflected sound is long enough in an echo to be
distinguished as separate by our ears.
In other words, the attack of the
direct sound and the attack of the reflected sound are far enough apart
in time for us to hear distinct taps. Some say it’s at about a 30ms
delay that reverb becomes echo and others say it’s a bit longer. Test
this for yourself using a reverb or delay plugin that allows you to
adjust the reverb time in milliseconds.
What’s the difference between reverb and delay?
We say delay when we refer to an effect
that produces echoes or distinct reflections or taps that you can hear
as quite separate from the original dry sound. This effect is quite
clear and obvious when you have a delay time of longer than a second.
the delay time down to 10-20ms and your initial reflection starts to
fuse into the original sound as your ear finds it impossible to
distinguish the two from each other. This is where a delay plugin can
start to sound like a short reverb.
Reverb is delay-based
effect. So, we use delay to create reverb. Multiply the reflections,
bring them much closer to each other in time and add some modulation and
you get very close to what we call reverb.
What is a reverb effect?
A reverb effect refers to either an analog or digital audio processor.
reverb unit or plugin simulates real reverberations by using delay on the
original source signal sent through it.
It allows you to then mix the
original or dry sound with the processed or wet sound.
real world reverb effects come in the form of reverb rack units,
built-in reverbs on guitar amps, guitar reverb pedals and of course
software reverb plugins.
Why is reverb important?
Reverb is what human ears use in part to judge the
distance of a sound source. It also plays a part in the positioning of
sound sources using our hearing.
We can use this handy fact as music producers or mixers to create the illusion on depth and space in our mixes.
What is reverb time or reverb decay?
Reverb time is the time it takes for the reverb sound to decay to nothing.
is, in a simple practical sense, measured in time from the first
reflection to where in the reverb tail resolves into silence.
technically it’s often measured as RT60 which you can read more about here.
Reverb is often shown as a diagram with an amplitude and a time axis.
See the diagram.
What is reverb diffusion?
Natural reverb is created by the shape of the confined
space in which it is formed. An empty square room with perfectly flat
concrete walls will have a different impulse response when compared to
the same room with furniture and other objects in it.
variation in surfaces causes a variation in the reflections which causes
a variation in the character of the impulse response.
simple terms, the more complex the nature of the room’s surfaces, the
higher the diffusion of the reverb or early reflections.
most digital reverb units or plugins diffusion is simulated by adjusting
various reverb parameters to alter the character of the reverb. More
diffusion on a plugin usually means reflections are closer to each other
which spreads or smoothes out the reverb sound. Less diffusion will
introduce more grain or twang, closer to traditional spring or plate
What does pre-delay do in reverb?
Pre-delay is a reverb parameter you’ll find in plugins. It allows
you to set the time between the dry impulse or sound and the
initial/first reflection. You’re telling the reverb unit, with this
setting, how long to wait before it starts the reverberated sound or
This parameter is useful when you want to create
separation between the dry and wet signals. Let’s say your vocal is
losing definition because of the reverb you’ve added. Try a longer
pre-delay which can help to make the vocal pop just a bit better.
What is wet reverb?
You can distinguish between the dry original and the wet effected
signal or sound. This is similar to the direct and reflected sound
waves in a natural acoustical space. Dry means no reverb and wet means
The balance between the dry and the wet signal is a
very important aspect of music production and mixing as it determines
the depth positioning and perceived size of the sound in your stereo
What is reverb damping?
Sound absorption and diffusion in natural spaces will
lessen high frequencies in reflected sound waves. This means that the
frequency distribution will be different depending on the space.
Reverb units or
plugins with a damping parameter allow you to simulate the effect
different surfaces will have in a natural space.
you have a wispy airy indie-girl vocalist in the mix. Leaving all her
high-frequency information in the wet reverb sound may cause the mix to
sound thin or scratchy. Increase the damping and your reverb becomes a
bit darker than the dry vocal sound. This gives the higher frequencies
in instruments behind the vocal reverb a bit more space and the whole
mix works better.
Should you put reverb on everything?
In short: No!
Here’s why you don’t really want to put reverb on everything…
instruments, like kicks and basses, have a lot of low-end information.
Reverb added on low and even low-mid frequencies can very quickly cause
issues in your mix.
A lot of the impact in a mix is caused by contrast. This applies to where you use or don't use reverb too.
Contrast a heavy reverb on your vocal with a little to no reverb on your main synth, for example. Add reverb to both and you're fast approaching a muddy mess.
How do you use reverb in a mix?
Reverb allows us to push an element back in the
mix depth-wise. It also allows you to put an instrument or sound in
it’s own psycho-acoustic space or in the same space as other sounds and
instruments in the mix.
percussive ping that plays on the first beat of the second last bar of
every eight bars. It sounds kind of rude, dry and abrupt in your mix.
You want to blend it into the mix, give it some depth and let it
linger a bit longer.
This is a short percussive sound. It’s
simple and only one tick long. This means you may want to add a bigger
reverb to contrast the short sound you’re working with.
want to make a lead sound blend in better with the comping piano sound
in your mix. Add a shorter room reverb to both sounds to place them in
the same space.
What is Convolution Reverb?
Convolution reverb simulates an acoustical space by using a recording of an impulse response of that space.
The exact mechanics get a bit too complex for this post. In short, however, we capture the impulse response of a room and save it. We can then use that response to create a reverb that simulates the space.
This type of reverb is different from straight algorithmic reverb plugins which use only algorithms to emulate the sound of spaces.