What Is Reverb?

Alright, hands up. Who's opened audio editing software and placed a reverb effect onto dialogue to make it sound like it's reverberating through a cathedral? 

While using reverb for playful effects can be fun, it's a powerful audio tool with meaningful, practical applications. Today, let's take a closer look at the world of reverb.

What is reverb? 

Reverb is the technical term for a sound originating in an enclosed space that sends sound waves outward. Those waves are then reflected off the surfaces of the space with a gradual decay. You know that empty sound feeling when you first enter an unfurnished room? The words you speak slightly linger in the air, bouncing off the bare walls before fading away. That’s reverb, as there are no objects to absorb the sound. 

Confusingly, however, this may also sound like the definition of an echo.

You would be right to think so; yet, how the sound carries with an echo is slightly different. These are both sound reflections, but the distance between the reflections differs. An echo is typically comprised of distant, repeated sounds heard after a brief delay. It generally lasts over 50 milliseconds, meaning the reflected sound has traveled at least 17 meters.

Conversely, reverb produces reflections that reach us a few milliseconds after the initial sound. These are early reflections, followed by a reverberant decay that tapers off over time. The reflection also blends in with the initial sound, whereas an echo is distinct, may even appear a second or so after the initial sound, and will echo many times.

If we could see sound, it would visually look like this:

Image via Lewis McGregor

The type of reverb that can be heard is directly influenced by the environment in which the sound is produced. For example, someone singing on a school stage would have a different reverb than someone singing in a cathedral. 

This important factor relates to how reverb is used digitally. See, within specialist audio editing software, which is referred to as a DAW (Digital Audio Workstation), you can apply reverb as an effect to individual audio clips or audio tracks. However, as we have established that reverb can differ depending on the space the sound originates from, it’s essential to recognize how the different settings work. Let’s break them down.

5 types of reverb effects  

1. Room reverb

Room reverb is your “everyday” echo, designed to mimic the sound of a small, real-world space. It’s subtle, so it’s excellent for grounded conversations in domestic or enclosed settings, such as a living room conversation or an argument in the manager's office. Drop some room reverb on the dialogue, and it’ll instantly feel more believable.   

In the video below from This is Onesto, he runs through nearly all reverbs mentioned within this list with auditory examples. Given the nature of this topic, we suggest listening to the examples so you can audibly hear the difference. 

2. Hall reverb

Hall reverb emulates the vastness of a concert hall. (As a side note, you’ll notice that most reverb effects are aptly named.) This is where we expect sound to travel, then reflect and decay slowly. It’s rich and somewhat dramatic. However, be careful, if you use too much, your audio becomes a mushy sound wall. It works well when you want a scene to feel atmospheric or cathedral-like.  

Image via Unsplash 

3. Spring reverb

Spring reverb is the sound of a literal spring shaken up by your audio signal. It’s metallic, unpredictable, and is loaded with that vintage twang. It's a go-to for electric instruments in guitar amps and some retro plugins. Like plate reverb, it’s not commonly used in film dialogue, but it can add character when the mix needs something a little more weird or nostalgic. 

4. Plate reverb

This refers to the mechanical process of a metal sheet vibrating in response to sound. It doesn’t aim to mimic real spaces, which makes it great for music, especially on vocals and snares, when you want something crisp and bright. However, again, it's not the go-to for dialogue, but it might be useful in a sci-fi mix or experimental track. It might just give your audio the edge it needs.

5. Chamber reverb

Chamber reverb originated from the literal practice of piping audio into an isolated room and recording the natural echo. Famous studios like Abbey Road used it all the time. It gives a smooth, rounded character without the mud of a hall. While this is primarily a music production tool, it could be applied to SFX to see what ghosts come back! 

With each available reverb effect, they will usually offer the same adjustable parameters, which are: 

• Pre-delay: Time between the original sound and the first reflections.
• Decay: The duration it takes for the reverb to fade out.
• Size: Simulates the dimensions of the space.
• Dry/Wet mix: This controls the balance between the dry (original) and wet (reverb) signals.
• EQ: Shapes the frequency to avoid muddiness.

In a way, shaping reverb is a lot like color grading, as you're constantly tweaking and adjusting parameters to dial in the exact tone you need.

Why use reverb?

So the question remains: Why use reverb? If you're capturing audio on location, should it not already have the natural reverb from the sound recording? And the answer to that is yes. You would not want to apply reverb to a dialogue recording with natural reverb unless for creative intentions. Some may even go to the extent of removing it if it’s too noticeable. 

Likewise, most of the above reverb effects are typically used in music production, not for dialogue. So…when do we apply it for filmmaking purposes? 

Are you familiar with this viral Hugh Jackman clip? 

It’s of Jackman recording ADR (automated dialogue replacement) for an action scene in the 2017 film “Logan.” ADR is a fundamental post-production process because film sets can be incredibly loud. For example, the video below shows how loud an IMAX camera is on set. Nearly all dialogue must be pre-recorded in these instances, as they're completely unusable. 

When ADR is required, dialogue is recorded in a professional sound booth, where the walls have been audio-treated so there is no reverb, echo, noise, etc. It's nothing but clear sound. This is done so the sound recordist can later shape the final sound exactly how they want. It gives them a clean foundation.

The issue is that, as seen in that Hugh Jackman clip, his screams and roars recorded in the ADR booth will sound incredibly unnatural when overlapping onto footage of Wolverine running through a forest. This is where reverb comes into play. 

This scream? Done in a studio. Image via Disney 

With reverb, sound editors can adjust all variable parameters to mimic the exact reverb type present on location. While the presets are a starting point for amateur users, accurately replicating the exact type of reverb that would have been present on location is an art within itself. 

Reverb for creative use 

However, it’s important to note that reverb isn't just used inherently to make ADR sound more realistic. It can add depth and spatial presence to sound effects and dialogue in scenes where standard, even realistic, audio processing falls flat. Perhaps no case study is more useful than “The Mummy” (2017).

You might think, "We were unaware that the film was such a temple of sound design." And well, that could be true. But the example we’re focusing on comes from a mistake in the trailer itself.

For some reason (how it slipped past so many key people is anyone’s guess), the initial trailer for “The Mummy” was uploaded to Universal Pictures’ official YouTube channel with several key audio tracks either muted or missing. As a result, only a few isolated sound elements made it into the final upload.

While a comical gaff, it makes for a fascinating study of how sound effects and dialogue can benefit from reverb, where creative liberties must be taken. 

In moments when Tom Cruise and his colleague are in the crashing plane, you can hear that a generous amount of reverb has been applied to many of their screams and tremors as they hurtle toward the ground. Now, of course, in an airplane that's on fire and plummeting, it would be anything but quiet, and even then, the confined space of the aircraft wouldn’t realistically allow for this level of reverb.

Yet, reverb helps blend the sound effects more organically, and importantly, its creative use here helps add a heightened sense of chaos and disorientation. This is how the trailer was supposed to sound. 

With all audio tracks now audible, it’s hard to imagine how this would have sounded with those clips appearing dry.  

So, while adding reverb to dialogue captured on location may sound irregular in most cases, in action and dramatic sequences, reverb can reinforce the emotional intensity of the moment beyond what realistic acoustics would allow.

For more on the world of audio editing, be sure to browse our Film School to continue your path of becoming a post-production guru.