Mixing: Reverb
Reverb is one of the most widely used effects in the world, yet most of the time, using it feels like a guessing game. In this article, we will teach you how to use reverb, which reverbs work well with different sounds, and help you understand what each parameter does - improving your production skills forever.
Reverberation, or ‘reverb’, is defined as a persistence of a sound after it’s produced.
Reverberation is created when a sound or signal is ‘reflected’ off of different physical objects, within a space. As numerous reflections build up, and then ‘decay’, sound is absorbed or reflected by the surfaces of objects.
Objects like furniture, people, and even air affect the tone and length of the reverb sound.
Each ‘reflection’ can be imagined as a short echo, whose tone and length is shaped by the object it ‘reflects’ off. Reverb is many small reflections, reflecting again and again off of different surfaces until the reverb ‘decays’ (fades away).
Imagine playing music from your phone. How does the music change if you place the phone in a wooden box? How does the sound reflect off the wood? How does this sound differ from for example, placing your phone in a metal box?
A graphic that shows the amplitude (volume) level of reverb over time, from initial sound (source signal), to the early reflections, reverb tail and decay over time. source: Mastering The Mix
How Do I Use Reverb?
To get the most out of using reverb effects, it’s important to understand how to use each control to shape the space you’re making. Each room has a shape - and they each affect the way sound reflects and bounces around within them.
Once you master the six parameters we mention in this article, you’ll be able to use reverb to add depth, space & width to your mix.
Apple’s updated look for ‘Space Designer’, the most popular reverb plug-in in Apple’s Logic Pro music production application.
Source: Apple
Early Reflections
These are the first reflections of a sound after it hits a wall, or a surface.
They’re clear, defined and happen before the full reverberation of a sound - so before the ‘decay’ These early reflections then bounce around the room and form the reverb tail.
a simplified graphic of how a sound creates early reflections and reverb, and how the sound interacts with the environment over time.
Source: Orchestra Music
Decay
As the sound reflects off different surfaces and materials, reflections build up and bounces around within the space. The sound eventually reaches the walls and then reflects back to your ears.
All these reflections together tell your brain the shape and size of the space you're in, or the reverb you’re placing your audio in. The decay time is how long it takes for those sounds to ‘decay’ (slowly fade) away. Decay time is measured in milliseconds (ms) or seconds (s).
this chart shows the volume changes from the initial sound source, early reflected sounds and collection of many reflected sounds.
credit: hyperphysics
Pre-Delay
Controlling the ‘pre-delay’ amount on your reverb plug-in changes how long it takes for the sound to produce those first reflections. Pre-delay is represented by time (seconds), and changing the value of this parameter shifts the position of the sound in the room; specifically how far away the sound is from the listener and the back wall of the room.
The larger the room is, the longer the pre-delay will be, as the signal travels further before reflecting off of different surfaces in the room (walls, ceilings, tables, etc).
Room Size
When you’re designing your reverb sound, there’s more ways than just ‘decay time’ to control the size of a room. The room size in digital reverb usually extends the time between reflections, as well as the duration of each reflection, giving an artificial boost to the size of your reverb.
Room Size can also be controlled by different parameters on digital reverbs, such as ‘Room Shape’, ‘Spread’ and ‘Spin’.
This graphic shows the average reverberation time (in seconds) of spaces that music is typically heard in. Source: Commerical Acoustics
Damping
Damping is probably the most misunderstood parameter of reverb effects. The damping effect is created when sound bounces off surfaces in a room, such as the floor, ceiling or curtains.
If the surface is hard, like a glass window or metal table, the reverberation will be bright and ‘hard’. With softer surfaces (e.g. wood vs concrete), the reverb will lose more high-end frequency information, resulting in a warmer sound. This means if your reverb sounds thin or too bright, you can use a damping effect to bring out the midrange and bass.
Diffusion
Diffusion is how dense the reflections in a reverb are, and how quickly they decay away into silence. Low values result in being able to hear early reflections more clearly. High values result in a more washy, smooth sounding reverb.
