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:

 
  • Cats are remarkably expressive creatures. And capturing their voices can be a daunting task. Not anymore…

    The “Meow” sound library provides all the core cat vocalizations you'll need in a single package.

    Using 11 different cats cherry picked for their characters, this library provides over 272 vocalizations for your productions.

    From sweet mewls, to longing cries, or vicious shrieks, this library has got you covered.

    This library also includes the Sonic Worlds “CAT” sound pack.

    Meet the beasts:

    JASPER
    A lunatic Calico. A treasure trove of enraged vocalizations.

    AFORI & FANGS
    Sweet natured Russian Blues for that soft gentle character.

    BASTARDO
    A nasty mean tomcat, hence his name. A Tabby with a rich growl.

    BOGART
    Deep threatening growls and hisses. A Ginger in a foul mood.

    GINGY & LUCIFER
    Whiny sounding Ginger cats. For those hungry begging cries.

    JESSICA
    Classic meows that work like a charm.

    MARTY
    A sad sounding Tabby cat. For those longing mewls that will break your heart.

    SWEETY
    An absolute sweetheart black cat. Purry meows galore.

    Cat sounds included:
    ● Screeches and Shrieks
    ● Snipes
    ● Yelps
    ● Mewls
    ● Cries
    ● Purrs
    ● Growls
    ● Grumbles, Groans and Moans
    ● Whining and Begging
    ● Hisses
    ● Squirms
    ● Meows in a huge variety of characters
    ● And more…
  • Space Space Racer – Pass-bys Play Track 62+ sounds included
    Rated 5.00 out of 5
    $15

    The Space Racer library features a diverse set of spaceship and pod racer pass-by sounds – designed for use in any futuristic sci-fi movies or video games. Strengthen your sci-fi sound design toolbox with this new collection – entirely edited at 96kHz, 24 bit, and embedded with Soundminer metadata.

    With over 60 sounds, you will find podracers of all shapes and technologies with massive flanging vehicles, quick stuttering pods, booming plasmic rumbles and much more.
    Whether you have an intergalactic competition or a more contentious extraterrestrial war, you will find your futuristic vehicle passbys here.

  • The Foleyart Collection | Extended Footsteps Collection is an Add-On for “The Foleyart Collection | Footsteps & Movements“. This package gives you access instantaneously to thousands more of high quality footsteps as WAV files, including different walking speeds, behaviours and surfaces.

    Foleyart Collection: Extended Footsteps –
    key features:

    • 8.848 real Foley sounds in HD quality @ 24Bit, 96 kHZ
    • 14 combinations of shoes and surfaces
    • Unique recording setup to adjust footstep distance
    • Different walking speeds and behaviors
    • All WAV files are Meta ready

    Includes the following surfaces:
    Asphalt • Diamond • Dirt • Grass • Dry Grass • Leaves • Metal • Rocks

    Includes the following shoes:
    Sneaker • Boot


Latest releases:  
  • 'Vintage Tape Machine' by resonant, features sounds from a Nagra 3 open reel tape recorder (1963 model.) Includes all switches, buttons, dials and running sounds both dry and with tapes playing, analogue hiss, winding and rewinding blank tapes and tapes with voices and tones, etc. Plus some fun DJ style 'scratching'.

    Switches can be slowed down to make bigger sounds, for example levers, or can be used as they are for organic user interface sounds.

    All sounds were recorded and mastered at 96k/24 bit and, of course, MONO!!

  • Mechanical Lifts & Elevators Play Track 223+ sounds included $32.50 $20

    The 'Lifts and Elevators' library contains a collection of sounds sourced from 19 different elevators. Each model bringing their own unique sonic qualities and character. From slick and smooth modern elevators to weathered old freight and goods lifts, these high-quality recordings have been carefully captured in:

    • Hotels
    • Offices
    • Studios
    • Flats/Apartments
    • Schools/Universities
    • Warehouses/Industrial Units

    Each elevator has been recorded in motion, opening and closing its doors (manually and mechanically), producing metallic rattles, creaks, groans and more. Additionally, Button pressing, alarm bells, buzzers and stationary room tones, have been captured in crystal clear detail.

    All sounds have been recorded in high-quality 24 bit, 96 kHz using Sound Devices recorders and Sennheiser MKH8040, MKH416 and MKH30 microphones. Each file has been also tagged with detailed Soundminer metadata to speed up workflow and increase organisation.

    The majority of recordings contain both a stereo MS decoded and ORTF version. The midside has a narrower stereo image whilst the ORTF provides a wider version.

    38 %
    OFF
    Ends 1525125600
  • Quadcopters / Drones Curious Drone-Quadcopter Play Track 60 sounds included, 30 mins total $20

    High quality unprocessed drone/quadcopter recorded using both binaural and mid-side microphone techniques. 4 different types of quadcopters were used in this sound library.

    Gear: Neumann KU-100 binaural dummy head microphone, Schoeps mid-side setup (Schoeps CMC6 MK8, Schoeps, CCM M4, Sound Devices Mix-Pre 6)

  • Sci-Fi Light Sabre Play Track 63 sounds included, 5+ mins total $9

    Ok, ok, before you hit the preview button…back in school a friend made a short film with lots of fighting and light sabres. Who doesn’t want to try their hand at making those? This was my valiant attempt as a fledgling sound designer. They ain't the real thing but perhaps useful nonetheless. Enjoy!

  • The Seagulls sfx library includes 28 tracks of both single, isolated seagull screams, and bigger flocks of nesting seagulls, calling out to each other and their chicks. There are plenty of classic call sounds, but also some weird throaty and raspy screaming, and what could sound like seagull laughing sounds.

    All tracks are recorded with the very useful zoom function of the Telinga microphone and dish.
    Library includes both untreated tracks, and noise reduction processed tracks in two separate folders. Noise reduction processed tracks have carefully been cleaned up with a CEDAR NR system.

    Though these birds are in an abundance around most harbours and industry around here, they are not always easy to record. You mostly hear them from a distance, or from places not easy to access. When you try to get close to them, they will usually fly away.

    Many hours have been spent on rooftops, gardens, backyards, a junkyard, and different harbours to get this material.


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:
  • Sci-Fi High Tech Interface Sounds Play Track 290 sounds included
    Rated 5.00 out of 5
    $30

    Looking for futuristic interface sounds? The High Tech Interface Sounds library is a targeted solution for just that. It features 280 sound effects in categories like Beeps, Buttons, Clicks, Data Processing, Micro High Tech and more – created by Sergey Eybog, who recently won an award for his user interface sound design.

  • Drones & Moods Tibetan Crystal Singing Bowls Play Track 93 sounds included, 43 mins total $16

    Tibetan Singing Bowls – The ancient brain entrainment methodology for healing and meditation. Tibetan Singing Bowls have been used for centuries for healing and meditation purposes. They create a range of sounds to restore the normal vibratory frequencies of diseased and out-of-harmony parts of the body, mind and soul. They are also used for sound baths, which is when participants lay on the floor and let the waves of sound from the Tibetan Singing Bowls wash over them.

    9 total bowls were recorded. Notes C, D, D#, E, F, G, A, A one octave up and B. A variety of bowl sizes were used from 8 to 12 inches.

  • Cats are remarkably expressive creatures. And capturing their voices can be a daunting task. Not anymore…

    The “Meow” sound library provides all the core cat vocalizations you'll need in a single package.

    Using 11 different cats cherry picked for their characters, this library provides over 272 vocalizations for your productions.

    From sweet mewls, to longing cries, or vicious shrieks, this library has got you covered.

    This library also includes the Sonic Worlds “CAT” sound pack.

    Meet the beasts:

    JASPER
    A lunatic Calico. A treasure trove of enraged vocalizations.

    AFORI & FANGS
    Sweet natured Russian Blues for that soft gentle character.

    BASTARDO
    A nasty mean tomcat, hence his name. A Tabby with a rich growl.

    BOGART
    Deep threatening growls and hisses. A Ginger in a foul mood.

    GINGY & LUCIFER
    Whiny sounding Ginger cats. For those hungry begging cries.

    JESSICA
    Classic meows that work like a charm.

    MARTY
    A sad sounding Tabby cat. For those longing mewls that will break your heart.

    SWEETY
    An absolute sweetheart black cat. Purry meows galore.

    Cat sounds included:
    ● Screeches and Shrieks
    ● Snipes
    ● Yelps
    ● Mewls
    ● Cries
    ● Purrs
    ● Growls
    ● Grumbles, Groans and Moans
    ● Whining and Begging
    ● Hisses
    ● Squirms
    ● Meows in a huge variety of characters
    ● And more…
Explore the full, unique collection here
 
   
FOLLOW OR SUBSCRIBE FOR THE LATEST IN FANTASTIC SOUND:
 
                              
 
GET THE MUCH-LOVED A SOUND EFFECT NEWSLETTER + 40 FREE SFX:
Just enter your details below to get the newsletter and free sound effects (soundlist):

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.