Understand the different types of reverb and how to best utilize each in order to enrich the sound design and mix of your film sound projects.
A film's soundtrack would not be successful without the use of reverb. This is because reverb is a natural occurrence which we experience everyday, and its absence would be noticed right away. Reverb helps ground and blend the sound elements of a film by “putting them in the space” and setting of cinematic scenes.
There are dozens of reverb types available – plate, spring, digital/algorithmic reverbs, linear reverbs, non-linear reverbs, and convolution reverbs – but how do they really work?
Sound artist Matt Yocum (Pet Sematary, The Cloverfield Paradox) focuses on the two main types of reverb that we often hear and use in audio post workflows: Algorithmic and Convolution Reverbs. He guides us through examples of each and the best uses to help augment our mixes.
While this video focuses specifically on audio post production for film, the concepts covered are relevant and useful for all sound artists.
Some terms in the video:
- Reverb - the result of sound reflecting off of one or more surfaces and then making its way back to our ears many times over. These reflections occur naturally around us all the time, even if the reflections are very short and not as noticeable as a more extreme example of standing in a cathedral or a gym.
- Direct Signal - The very first occurrence of a sound event, before we hear any reverb reflections.
- Dry vs Wet Signal - Dry sound specifies sound which has not been processed by reverb or any other effect, as opposed to Wet sound, which has been artificially manipulated and changed.
- Impulse Response - is the outcome of a brief impulse (such as a balloon pop) reaction within a room. Every room has a unique impulse response.
- Transient - the first short-lived burst of energy of a waveform, such as those caused by consonants in human speech.
- Panning - the positioning of sound on different sides of the sound field; ex. left or right.
- Tail - the end of a signal or waveform.
- Decay - the means by which sound fades into silence.
Reverb is integral to the immersive experience because it has the ability to place all of the different sound elements of a film into the physical space portrayed on screen, and replicate the way we would experience them in the natural world. Reverb not only shapes the space we are in, but also helps to identify distance which is a crucial tool for audio. In addition to replicating natural phenomenon, reverb also has the ability to shape the narrative content of a film, and can influence the way a story is told by placing listeners into the psychological space of the characters by manipulating the tone and creating contrast.
Algorithmic reverbs are any digital reverbs which give you an adjustable set of parameters that you can then manipulate and change, in order to alter the physical characteristics of the reflections you are hearing. They are great for quickly dialing in settings to emulate the type of reverb you want for any given space or scenario. Algorithmic reverbs are so commonly used because they offer so much flexibility.
Convolution reverbs are the "sonic blueprints" of spaces, which we can then feed our sound elements through during post. These sonic blueprints are created by capturing the impulse responses of rooms — those impulse responses are created by running a sine wave sweep through a space and then phase cancelling out the tone. Impulse responses can also be captured by recording a single full spectrum transient, such as a gunshot or a balloon pop. Because impulse responses are recorded in real spaces, they also have the irregularities and “randomness” that you hear in natural settings and therefore offer a very convincing and realistic reverb.
In most cases reverb is used to create a sense of natural space and depth in a mix. Reverb can put sound effects or designed elements into the same sonic space as the production sound, and therefore makes a listener believe the sound is all taking place within a certain environment. Matt demonstrates the ways that reverb can embellish a mix in both exterior and interior shots by processing character footsteps. By using reverb, he can manipulate the size of a space and demonstrate distance and off-screen movement. Matt also demonstrates the way in which reverb can be used to process the music in a film by processing a track of diegetic music.
Reverb is an essential part of your mix and is the perfect tool to create space, story, and contrast in your film. There are so many options for how to use reverb, and the best way to learn is through your own experimentation — the possibilities are endless.
Here's the link to Matt's film template which can also be found in a previous blog post of his: File Management Tips for Organized Pro Tools Sessions
Matt Yocum is a sound artist based out of Los Angeles.