What is reverb? | The parameters and main use cases of digital reverb

Allowing us to establish a sense of space, reverb is one of the most popular effects used in music.

Today, we turn our attention towards reverb, exploring what it is and identifying its common types, parameters, and best practices.

What is reverb?

We hear reverb every day. Most of our surroundings reflect sound, and at any given moment we’re bombarded by these sonic reflections. If we stand in an empty hall and clap, we hear a mixture of direct sound (sound that travels straight to your ears) and reflected sound (sound that radiates, bounces off of walls and other objects, and travels back to your ears). We interpret this mixture of reflections to perceive the nature of the space we are in. Thus, we mostly use reverb in our productions to simulate spaces, although there are plenty of other creative uses for it.

Let’s take a listen to what reverb sounds like in the context of music. Below is a vocal sample without any reverb:

      

And here’s what it sounds like with the addition of digital reverb:

      

Notice how the vocal with reverb sounds like it was recorded in a large space. While the effect is highly noticeable in the example, it can also be used in far more subtle ways.

Digital reverb types

Most of the reverbs we use now are digital models. Unless you own a large studio and have the space to create your own reverb chamber, we’re going to have to primarily rely on digital reverb plugins. Here’s a list of the different types of reverbs and a brief explanation of what makes each one unique.

  1. Hall / chamber
    • These reverbs simulate spaces as if you’re in a hall or chamber.
    • A hall usually has a longer reverb time of around 1.8 seconds or more, while a chamber is typically a smaller space with a shorter reverb time.
    • There are plenty of famous concert halls out there such as the Berlin Symphony Hall and Boston Symphony Hall, and many digital reverb units try to simulate these spaces.
  2. Plate 
    • A plate reverb is a man-made device that vibrates a sheet of metal when a sound activates the surface.
    • Plate reverbs were particularly popular in the ’60s, and both analog versions and digital emulations are still widely used today. They’re known to work well with vocals and drums in particular.
    • One of the best digital plate reverbs out there is Universal Audio’s EMT 140, their re-make of the physical EMT 140 plate.
  3. Convolution
    • A convolution reverb makes use of a recorded sample, called an impulse response, of an existing acoustic environment. This impulse response essentially records and processes the reverberant behavior of a particular space.
    • Anyone can create an impulse response of an acoustic space and load it into a convolution reverb (though doing it well is more difficult). Audio Ease’s Altiverb contains some of the best convolution reverbs of magnificent acoustic locations that are certainly worth checking out.

The parameters of digital reverb

Although there are many types of reverbs out there, they share a few common core parameters. Let’s define and visualize the relationship between some of these characteristics.

A graph that visualizes reverb, with the Y axis representing amplitude and the X axis representing decay. The graph shows that as decay occurs, the amplitude of reverb decreases.

  1. Decay: Also known as the reverb time, RT60, or reverb tail, this parameter tells you how long it takes for a reverb to fall by a certain level (60 dB). The longer the decay time, the longer you would hear the reverb linger in your mix.
  2. Early reflections: Early reflections are the first group of reflections that occur when sound waves hit an object. More pronounced early reflections will perceptually place your listener in a small room, while a lower early reflection level will place your listener further away in your acoustic space.
  3. Pre-delay: The pre-delay is the amount of time it takes for a sound to leave its source and create its first reflection. Having a slight pre-delay allows you to separate the dry and wet signals and prevents the reverb from masking the original signal. A reverb with a significant pre-delay will cause the listener to feel that they’re in a big space.
  4. High / low frequency attenuation: Most reverbs have the ability to use some sort of a filter to attenuate high and low frequencies. If you find that your reverb sounds too bright or too metallic, try filtering it with a low pass filter at around 4 – 8 kHz. Similarly, using a high pass of up to 450 Hz can help clean up your reverb and reduce muddiness.
  5. Mix: The mix setting on reverbs allows you to adjust the balance between the dry (original) and wet (reverb) signals. If you’re using a reverb as an insert, use the mix setting to adjust the dry / wet ratio. If you’re using it as an aux send on a track, set the reverb mix to 100% so that you would only hear the reverb signal.

Best practices for using reverb

Below are some best practices for using digital reverb in the DAW.

  1. To preserve CPU resources, it would be wise to share a single instance of your digital reverb across multiple instruments. To do so, simply create an aux track and have the reverb as an insert on that track with a mix setting at 100%. This allows you to send many instruments to the same reverb, instead of putting many instances of the same reverb on each individual track.
  2. Using too much reverb or having too long of a reverb time can blur your mix. For example, a percussive sound may sound less dynamic when drenched in reverb. Use reverb sparingly and wisely. If you find a sound disappearing in the mix or lacking definition, try changing the reverb setting or not feeding it any reverb at all.

Do you have any questions about reverb? Leave them in the comments below.

July 29, 2020

Reuben Raman Product Marketing Manager at Splice