A Guide to Reverb and How It Works

The effect of reverb as represented on a graph
Mixing

Sound travels from a source in all directions and reflects off the surfaces found in the room/spaceReverb is the name given to the ambient sounds produced by the sound waves that bounce off the internal surfaces of a room, and I think it’s one of the most important tools you have in the studio.

It’s definitely one of the most commonly used, as it helps to ‘glue’ together all of the different tracks. To achieve this, the effect is added at the mixing stage after recording has taken place, and there are countless plugins and units available to do the job.

Most sounds you hear are directional, but sound actually travels out from a source in all directions. As the sound waves travel out, they hit surfaces (walls, ceilings, floors, etc.) and bounce back into the room. These reflections aren’t heard individually – they’re so closely spaced together that they merge into a single sound.

 


The Reverberation Effect

 

Most of the instruments and vocals in your home studio will be recorded closely and direct, due to the limits you’ll probably have with available space. However, it’s quite unnatural for us to hear these sounds in such a dry and direct way as that’s not the way we naturally hear sound in the real world.

The effect is used and applied during mixing to help create a space or a room for all the tracks to sit in – artificially re-creating the way that we hear sound in the real world. These artificial creations can range from realistic spaces like concert halls or bathrooms, to more outlandish options like a cave.

Each effect, or patch, on an effects unit or plugin will have parameters that control the different characteristics of a space. Three of the elements that affect the sound produced are:

  • Room surfaces: how absorbent or how reflective a surface is. The most absorbent surfaces are things like carpets and curtains (which is why they’re used as furniture to deaden a room), and higher frequencies get absorbed more easily than lower frequencies.
  • Room size: this governs how quickly the reflections will be heard and how long they will last. The larger the room, the longer it takes to hear the first part of the effect.
  • Room shape: you can get regular or irregular shaped rooms, which determines how the sound ‘spreads out’.

 


Effect Settings

 

A digital effects unit or plugin has a few standard parameters that can control and shape the sound that you apply to your mixes and productions, so it can mimic the different characteristics of a room.

They can range from standard rooms to highly imaginative rooms and spaces (you can even get units and plugins that offer ‘Grand Canyon’ type effects). There’s really no limit to the sorts of spaces you can emulate.

 

The effect of reverb as represented on a graph

 

Some of the most common parameters are:

  • HF Damping/Decay: based on a lo-pass filter, this mirrors the behavior of the room’s surfaces and how reflective they are.
  • Early reflections: the time it takes for the first reflections to bounce back to you after the direct sound, which mirrors the size of the space.
  • Pre-delay: the time between the direct sound and the early reflections, mirroring the size of the space.
  • Diffusion: how the effect widens across the stereo image, mirroring the shape of the space.
  • Reverb time: the overall time it takes for the effect’s sound to disperse, which is another control that can mimic the size of the space that you’re creating.

 


Final Thoughts

 

The first key to using reverb successfully is understanding what it is and how it works. Once you know what it’s all about, it becomes a lot easier to apply to your mixes and productions, both technically and creatively.