procedural game audio Asbjoern Andersen


How do you keep your game audio varied – without needing countless individual audio files? Procedural sound design can help with exactly that, and in this hands-on guide, senior lecturer, teacher fellow and author of the Game Audio Implementation book, Richard Stevens, demonstrates how the concept works in the Unreal Engine.

When creating a sound effect for a movie you’ll know that the audience is only going to hear it on one specific occasion, and you’ll likely build it up through editing and layering different sound elements to get just what you want.

01_game_audio_Explosion

Figure 01 ‘An explosion’

 

Most games, like sports, are about skill and mastery, so the player will be repeating similar actions again and again, and consequently they will be hearing the same sounds again and again. The trouble is that we’re very sensitive to this kind of repetition, since it just doesn’t happen in real life.
 

Video Thumbnail

Video: Explosion Baked


 
The obvious answer is just to have loads and loads of sounds but it would be far too much work to create 30-40 versions of every sound in the game (plus there are obviously limitations as to how much we can fit on a disk!).
If we look at our ‘explosion’ sound again we can see that the final sound is made up of different characteristic components, and this idea is key to starting to think about procedural approaches to sound design.

02_game_audio_Explosion_Components

Figure 02 ‘Explosion Components’

What we want to do is to keep these components separate when we import them into a game so that we can recombine them in different ways at run time. A lot of sounds in games aren’t ‘sounds’ at all, they are systems of sounds. This kind of procedural approach requires a different way of thinking, and sometimes different kinds of sound assets, since we often want to isolate the individual components that make up a sound.

When we bring these components into a Sound Cue in the Unreal Engine we can build a system of playback, and by having a few different versions of each component we can randomly combine them to create variation.

03_game_audio_Procedural_Explosion

Figure 03 ‘Procedural Explosion’

 

Video Thumbnail

Video: Explosion Components


 
By taking this approach we don’t need thousands of complete sounds in our game to be able to get thousands of different sounds out of the system. Randomizing the combinations of layers can vastly increase the number of potential outcomes with only a few additional sounds.

By taking this approach we don’t need thousands of complete sounds in our game to be able to get thousands of different sounds out of the system

In the above example we have four sets of three possible sounds that can potentially be heard so this will give us 81different sound outcomes. If we added just one other ‘Crack’ element then we’d get 108 potential sounds.


WANT MORE LIKE THIS?
FOLLOW A SOUND EFFECT FOR THE LATEST IN FANTASTIC SOUND:
 
          

We can increase this variation even more by adding some slight randomized delays and modulations of pitch and volume to each element, giving us.. erm… a very large number of possible outputs.

04_game_audio_Delay_Mod

Figure 04 ‘Adding Delay and Modulation nodes’

Video Thumbnail

Video: Explosion Delays and Modulation


 

Another thing we might want to do is to change the sound depending on what was being blown up, or the materials of nearby objects. Again by keeping these material components separate we can choose to layer them into the Sound Cue when appropriate by using a switch.
 


Popular on A Sound Effect right now - article continues below:

 

Latest releases:  
  • Sci-Fi Beams Play Track 1139 sounds included $149 $99

    BEAMS is a comprehensive toolkit for beam sound design. Sounds are separated into activation oneshot, activation/deactivation mechanism, and active loop categories. Each category contains subcategories for small, medium, and large beams. You can design anything from the smallest spy-watch laser cutter to a planet destroying column of chaos. As a bonus, you’ll also get a diverse collection of burning ignition sounds as source for beam environmental destruction.

    34 %
    OFF
    Ends 1597442399
    Add to cart
  • Metal Smash – What do you get when you go to the junkyard with the best Schoeps Microphones money can buy.

    Every effect is also recorded with a sub sonic microphone to add depth to the smashes. Great complicated crashes with extra metallic details.

    20 %
    OFF
    Ends 1597355999
    Add to cart
  • The sounds presented in this pack were recorded during the shooting of a short film taking place by the ocean. We shot in different places, in the marina, on a boat, in an industrial harbor area, in a wharehouse of boat maintenance.

    Even if some sounds of the pack are not fully in the theme, I voluntarily left them because they were recorded at the same time and in order to serve the film.

    The most represented sounds in this pack are those recorded in the marina, the wind blowing in the masts of the boats, at the seaside, as well as a detailed recording of the zodiac boat.

    Sounds were recorded using Sound Devices 633, in 24bits 96Khz, Schoeps CCM 21 mic in ORTF, with an extra CCM 41 for the center (LCR), and using an extra contact mic to record the motor of the zodiac boat.

    All the sounds are raw (No EQ, No Compression, No Fx).

    This pack contains 40 sounds, 80 files, for the ambiences.

    It also contains 15 sounds, 39 files for the zodiac boat.

    All embedded with detailed metadata on Soundminer.

    Add to cart
  • Welcome to “MOTION MODE”, an intense collection of sounds to induce movement and evoke excitement in your production.

    You will find whooshes, transitions, noises, granular textures, movements, stutters and hits with a powerful Sci-fi feel.

    Special attention was put in the dynamics of the sounds to ensure the creation of an energetic pack aimed to enhance atmospheres, add movement and enrich musical compositions.

    If you liked some of my previous libraries like “Dodge this” and “The Transition” you are gonna love this one.

    29 %
    OFF
    Ends 1597183199
    Add to cart
  • Huge deep and textural organic whoosh by’s. These are un-altered but a total blast. Want more fun, just (again) compress and pitch to fit, and hell, maybe add a little distortion.

    A great collection of organic sliding whooshes. They sound great, have lots of movement and are almost always complicated movements not just simple whoosh by’s.

    20 %
    OFF
    Ends 1597183199
    Add to cart


Need specific sound effects? Try a search below:
 

By getting information from the game about what type of material is being blown up we can use this to control the switch, and therefore which material components of sound get added to the overall explosion sound.

05_game_audio_Explosion_Materials

Figure 05 ‘Explosion Materials’

Thoughts on the term ‘Procedural Sound Design’:

In writing the book we made a conscious decision to term this kind of sound design, that is typical in the current practice of game audio, ‘Procedural Sound Design’ to differentiate it from ‘Procedural Audio’.

Andy Farnell, who coined or at least popularised the term ‘Procedural Audio’ sees it as any kind of system where the sound produced is the result of a process. He describes these ideas more fully here. So under that definition, as soon as you set up any kind of system of playback you could see it as being procedural audio.

However there has been a lot of important work and progress in terms of procedural audio for games in the last few years (see http://proceduralaudionow.com/), and this has encompassed a variety of techniques, but there has been some emphasis on the idea of these procedural systems being synthesis based, which ultimately is probably the most flexible solution for interactivity.

This is a specialist field which we don’t go into in any depth in the book since there are other great books out there on this (not least Andy’s book ‘Designing Sound’). In the book we attempt to describe the range of procedural approaches by saying, “This approach to sound design exists on a spectrum from procedural sound design, where we tend to be manipulating pre-existing assets, to procedural audio, a term more frequently used when systems of synthesis are used to generate the sounds themselves (with much in between that combine both approaches)”.

To throw another thing into the discussion, when discussing music systems we also use the term algorithmic, which again could be used to describe any kind of system of playback. Although we could just call this procedural music (as others such as Karen Collins have done), but we felt it worth preserving and highlighting ‘algorithmic’ given the long history of algorithmic techniques explored for music in the past, which a search for ‘procedural music’ is going to miss.

 

Video Thumbnail

Video: Explosion Materials


 

Now we have all the elements of a sound as separate components we can also do other things with them, like spatialize them around the player in different ways. For the Game Audio Implementation book we built a simple system that will throw sounds around the player for people listening in 5.1 or 7.1. This could be used for elements of the explosion itself or for debris.

06_game_audio_Spatialized_Diagram

Figure 06 Diagram

 

07_game_audio_Spatialized_Detail

Figure 07 Detail

 

This was done in Unreal’s Blueprint system – which looks a bit daunting at first but once you get the hang of it you can pretty much do anything you might dream up!

08_game_audio_Blueprint

Figure 08 Blueprint

 

Video Thumbnail

Video: Explosion Spatialized


 
By using a procedural approach to sound design we now have an explosion sound that’s different each time, is ‘aware’ of the different materials involved in the explosion, and spatializes around the player in stereo, 5.1 or 7.1.
 

A big thanks to Richard Stevens for his insights on procedural game audio! If you want to know more about procedural sound design for games then check out the Game Audio Implementation book from Focal Press. If you’re new to UE4 you can get UE4 here for free, and you can download all the levels that go alongside the book here (also for free!) to get started.
 

Please share this:


 


 
 
THE WORLD’S EASIEST WAY TO GET INDEPENDENT SOUND EFFECTS:
 
A Sound Effect gives you easy access to an absolutely huge sound effects catalog
from a myriad of independent sound creators, all covered by one license agreement
- a few highlights:
  • Destruction & Impact Metamorphosis Play Track 2328 sounds included $190 $165

    Metamorphosis is a huge collection of recorded source, synthesized material and hybrid sounds. The library was created to cover a wide range of themes, with rich textures, aggressive impacts and a large selection of pass bys, bass drops, pyrotechnics and many more types of material.

    All of the Recorded Section was captured at 384KHz with microphones capable of recording up to 200KHz among with more conventional mics. The resulting assets are sounds that can be stretched to new extremes for greater sound design opportunities.
    In many cases I took the liberty to slow down the assets while editing the sounds to deliver what I thought was the most useful version of a given recording though in most cases I have also included other takes at the original 384KHz sample rate to get the best of both worlds.

    All of the Synthesized Content was created in Serum while the Hybrid Section was created by manipulating the Recorded and Synthesized sounds.

    Techniques such as morphing were used to blur the lines in between the nature of the two sources, making for ambiguous yet extremely versatile material that can be employed on both realistic and abstract designs.

    Bonus: Two extra libraries included for free:
    This library also includes two additional releases from Mattia Cellotto - for free: Crunch Mode delivers 230 crunchy sounds made with a variety of vegetables, fresh bread, pizza crust and a selection of frozen goods. The Borax Experiment gets you 158 squishy, gory, slimy and gooey sounds.
    13 %
    OFF
    Add to cart
  • Animals & Creatures Animal Hyperrealism Vol I Play Track Over 1300 sounds included $170 $140

    Animal Hyperrealism Vol I is a library containing sounds themed animal vocalisations, from real to designed creatures totaling more than 1300 individual sounds in 290 files.

    The sounds were partly recorded with animals trained for media production, partly recorded in zoos and wildlife centers. The asset list includes but is not limited to: african lions, bengal tigers, horses, donkeys, cows, exotic birds, owls, bobcats, pumas, dromedaries, wolves, dogs, geese, lemurs, gibbons and many more.

    All the content has been recorded at 192KHz with a Sanken CO100K plus a Sennheiser 8050 for center image and a couple of Sennheiser MKH8040 for stereo image. All files are delivered as stereo bounce of these four mics, though in some instances an additional couple of CO100K was added to the sides.

    The resulting ultrasonic spectrum is rich and allows for truly extreme manipulation of the content.

    Bonus: Two extra libraries included for free:
    This library also includes two additional releases from Mattia Cellotto - for free: Crunch Mode delivers 230 crunchy sounds made with a variety of vegetables, fresh bread, pizza crust and a selection of frozen goods. The Borax Experiment gets you 158 squishy, gory, slimy and gooey sounds.
    18 %
    OFF
    Add to cart
  • Animals & Creatures Animal Hyperrealism Vol II Play Track Over 2000 sounds included $170 $140

    Animal Hyperrealism Vol II is a library containing sounds themed animal vocalisations, from real to designed creatures totaling more than 2000 individual sounds in 283 files.

    The sounds were partly recorded with animals trained for media production, partly recorded in zoos and wildlife centers. The asset list includes but is not limited to: amur leopards, bottlenose dolphins, californian sealions, pacific walruses, red ruffed lemurs, owls, parrots, dwarf little fruit bats, hamsters, guinea pigs and many more.

    The content has been recorded at 192KHz with a Sanken CO100K plus a Sennheiser 8050 for center image and a couple of Sennheiser MKH8040 for stereo image.
    A special section of the library features samples recorded at 384KHz. For these sounds an additional microphone was employed, specifically the CMPA by Avisoft-Bioacoustics which records up to 200 KHz. This microphone was actually used to record most of the library but the 384KHz format was preserved only where energy was found beyond 96KHz not to occupy unnecessary disk space.
    All files are delivered as stereo bounce of these for mics, though in some instances an additional couple of CO100K was added to the sides.
    The resulting ultrasonic spectrum is rich and allows for truly extreme manipulation of the content.

    Bonus: Two extra libraries included for free:
    This library also includes two additional releases from Mattia Cellotto - for free: Crunch Mode delivers 230 crunchy sounds made with a variety of vegetables, fresh bread, pizza crust and a selection of frozen goods. The Borax Experiment gets you 158 squishy, gory, slimy and gooey sounds.
    18 %
    OFF
    Add to cart
Explore the full, unique collection here
 
   
FOLLOW OR SUBSCRIBE FOR THE LATEST IN FANTASTIC SOUND:
 
                              
 
GET THE MUCH-LOVED A SOUND EFFECT NEWSLETTER:
 
The A Sound Effect newsletter gets you a wealth of exclusive stories and insights
+ free sounds with every issue:
 
Subscribe here for free SFX with every issue

3 thoughts on “Why Procedural Game Sound Design is so useful – demonstrated in the Unreal Engine

Leave a Reply

Your email address will not be published. Required fields are marked *

HTML tags are not allowed.