By Bob Kirschner, CMD’s chief mixer/sound designer
So you’re working on a post project and you’d like to do something more with the audio than just have a music track play under the dialog. Sound design can be used to add a range of elements to enhance your project. This post will help to explain sound design, and offer explanations and links to inspire you to try out some new things.
What is Sound Design?
Sound design is the art of creating or manipulating sounds for a variety of needs. For our purposes in audio post production, sound design can be divided into two broad areas - backgrounds and hard sound effects.
Backgrounds, or ambiences, are typically added to create the sound of a specific location where your project is taking place. These can be broken down to two groups: exterior and interior sounds. Backgrounds don’t need to be realistic - they can also be synthetic sounds that aren’t meant to simulate a natural space. Examples of exterior ambiences are street traffic, the sound of a jungle at night, a playground, or a wind-swept prairie. Interior ambiences would include the sounds of a bar, a factory, or an airport terminal, as well as room tones (the static sounds of empty spaces). A good example of synthetic sound design is the sound of outer space - something that sound designers create from their imagination, since space is a vacuum and doesn’t carry sound waves.
Hard sound effects are specific sounds such as an explosion, a jet plane fly-by, an alarm clock ringing, or a computer notification tone. These are typically processed in post production to sound like they are located in whatever environment is needed. So a distant gunshot would have a completely different sonic character than the same gunshot close up.
Supporting The Visuals in Post Production
Whether you’re working on a narrative film, a TV spot, or a sizzle reel, sound design almost always takes its cues from the visuals. Sound designers will often start with a spotting session where they watch the visuals and identify which scenes of the project can use sound design - creating an outline of sound needs.
Some elements will be fairly obvious, like whooshes that emphasize a motion graphic effect in a sizzle reel or promo. Or the need to build natural backgrounds for locations that don’t have good production sound. Or footsteps that need to be foleyed (foley is the art of performing & recording sound effects while matching the action onscreen). Other ideas may not seem obvious at first but can end up becoming a trademark sound, like the breathing of Star Wars’ Darth Vader.
Creating The Sounds
So what are your options for acquiring sounds that can be used for sound design? I’ll discuss three common ways to source sounds:
Pre-recorded sound effects libraries. There are many companies that offer excellent quality sound effects for purchase. When you purchase a sound effect, the cost includes the usage license so no additional costs are required when they are used in a project. These purchases can be complete libraries already grouped into categories like ambiences, transportation, war, cartoons, etc. Many companies also sell one-off sound effects, or offer sound effects on a subscription basis. Popular companies include Sound Ideas, Audio Jungle, and Pro Sound Effects. And you don’t have to spend money to source pre-recorded effects - there are websites that offer free sound effects, as well as many You Tube channels that stream sound effect beds.
Production sound. If you’re working on a project that has production sound recorded on location or on set, you can use this audio for a range of things. Room tones and interior or exterior ambiences can be extracted and looped to create backgrounds. Layer a few loops and experiment with different balances and tone settings to create unique combinations. Dialog can also be used to create special effects for dreamy or dark sequences. Process the dialog with filters and delays to create unusual elements that can be placed in key moments.
Custom Recording. The best way to create unique sound design is by recording your own sounds. Portable field recorders are commonly used for going out and capturing sounds, although anyone with a decent USB mic can easily record sounds on a laptop or portable device. Recording your sounds from scratch ensures that you are bringing a unique source to your project, and is standard practice when designing sound for films. One type of sound effect recording is foley, which is the specific practice of performing sounds in real time, matching the onscreen action. If you think about footsteps, punches, or sword fights, it’s practically impossible to use prerecorded sound effects to portray action like this in a believable manner. A foley artist can precisely mimic the onscreen action and create sounds using everyday objects that naturally match the dynamics of the action. Have a look at this clip for a cool look at foley artists in action.
Editing, Processing and Mixing Your Sounds
After acquiring your sounds, be sure to get creative when editing them into your project. Have fun with this, use trial and error, and don’t necessarily stick with what seems obvious. Rather than using a single sound effect, be sure to try layering a number of sounds and experiment with different balances. Hybrid sounds can give your overall sound design a unique quality and help to make it stand out.
Processing and mixing these sounds is key to a successful sound design. There are endless audio processors available to manipulate sounds, but if you keep in mind a few fundamental concepts it will help to make decisions on how to approach a situation.
Most audio processing affects one (or more) of these basic characteristics: pitch, timbre (tone), and spacial placement (depth and/or width).
Try pitch change to alter the characteristic of a sound: pitch a sound up to make it bright and cutting; pitch it down to go deep and ominous. Need an unusual lion roar? Take a cat’s meow and pitch it down by an octave, then add another layer two octaves down. Changing the pitch of a sound typically changes the sound’s speed as well, although there are options for pitch change without a change in speed. If you ever need to change the length of a sound effect, pitch change is an easy way to slow down or speed up a sound. Vari-pitch effects will change the pitch gradually, and result in what sounds like slowing down or speeding up a sound over time.
One classic example of sound design using pitch change is in Martin Scorsese’s infamous feature Raging Bull. Animal sounds like elephant brays, lion roars and horse snorts were processed to enhance the boxing matches, to a disturbing degree. Have a look at this clip to see what I mean.
Timbre is the tonal quality of a sound, it’s what contributes to a sounds’ character. Someone whistling is making a mostly “pure” sound with a simple tonal character. Someone playing fuzz guitar through a wah wah pedal is making a highly complex sound with tons of overtones and filter sweeps. Any simple sound can be made more complex by using processors like saturation, modulation and filter resonance. And vice versa, a highly complex sound can be mellowed out by using any number of filters and other effects.
To dig a bit deeper lets talk electronic music. Synthesizers generate a myriad of sound types, from lush pads and cutting leads, to emulating acoustic instruments and creating a huge range of sound effects. The basic building blocks of analog synthesis are a set of just four unique sound waves: a sine wave, a triangle wave, a square wave and a sawtooth wave. The character of these waveforms range from pure and simple (a sine wave) to highly complex (a sawtooth wave). Practically any sound can be generated from these four building blocks. Check out this website to see and hear these waveforms in action. Understanding waveforms will go a long way in learning to create and manipulate sound.
How a sound is placed spatially is a crucial part of sound design. Spatial placement, or depth, means that something can sound “in your face” (dry), or it can be part of a distant atmosphere (wet). Sounds are typically recorded dry because it’s easy to process a dry sound to make it seem like it’s coming from any imagined environment, from the tight sound of a small bathroom to the distant echos of a massive church. Think of ‘depth’ as a way of imagining a space for a sound, as well as where the sound is within that space. So, from a listener’s perspective, what tells us that something is closer to us, or farther away? The key is the amount and type of reflections that we hear with the sound. And these reflections are what audio processors use to let sound designers manipulate and process sound.
One of the coolest audio processors for placing sounds within a specific environment is Convolution Reverb. Convolution Reverb simulates the ‘sound’, or environment of a physical place, through software profiles. To create these environments, the actual sound of a location is used to cature a recording, which then generates an Impulse Response - a digital version of the reflections of that environment. With these profiles, you can take the dry recording of someone walking, and apply different Impulse Responses to hear that sound walking on an empty street, or in the hallway outside of a closed door. You can hear dialog spoken in a living room, or on a beach. Each location has a unique response that models the reflections of that place. And these software models are unbelievably realistic sounding!
The convolution reverb program best known for providing a huge range of high quality impulse responses is Altiverb, by Audio Ease. Check out this demonstration video to listen to different medelled spaces, and to get an idea of how impulse responses are created. Perhaps you’ll be so enthusiastic that you’ll start creating your own collection of custom IR’s! (easily done) or maybe you’ll write your thesis paper on convolution reverb (true story from an audio intern of mine after I introduced him to this subject!)
Well I hope this article helps to explain the basics of sound design, and motivates you to explore some new ideas. Sound design is an art of endless possibilities - be creative and have fun!