Team Project Portfolio: Procedural Audio

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Procedural Audio is a non-linear approach to sound design where instead of creating a standard static sound, instead you create a program that changes parameters of a sound at runtime to produce a large variety of sounds. (Farnell, 2007)

Procedural audio allows us to take information from the game at run time and let it affect our soundtrack. Instead of having to make a large library of enemy attack sounds, instead, you would make a program that will take the one base sound and alter it heavily depending on the parameters you give it. It could be the velocity of the attacker as they strike, it could be who they're striking, it could be what kind of attack it is. Instead of having a different sound trying to cover every possible outcome, you're designing a procedural audio program that can take these things into account and modify the sound as necessary.

Procedural audio, while extremely versatile does have a prominent setback, which is that since it is making these adjustments at run-time, it can be quite CPU-intensive. That and these programs are typically not uncomplicated and require much time to develop and make effective, so it is important to apply a Procedural Audio approach where appropriate, instead of trying to do everything with it.

Something that procedural audio deals with very well is avoiding repetition. If you were going to make a sound effect like for example a player's footsteps, you might want to make a small selection of footsteps for each type of material they might walk on. You might also want to get some of them walking fast, slow, running, sneaking, etc. However, with a procedural audio approach, we can take things such as the player's speed, the material of the floor they're walking on and adjust the sound appropriately, furthermore we use those parameters to give us ranges of values, then use random selection between those ranges in order to get even more combinations, that way your ear is never listening to the same footsteps again and again, or the same attack sound again and again. Immersion is retained and monotony avoided.

So what sounds in the Thinking City make for good Procedural Audio candidates? Repetitive sounds. Sounds that are likely to become monotonous and irritating as they play over and over again. (Fournel, 2010) The player's footsteps, for one. The movement of the enemy bots, the attack sound effects of the robots and the impact of the attacks on the player when they hit.

There are numerous procedural audio tools available such as Reaktor, Max DSP, and Pure Data. Pure Data is the tool I'll be utilizing in my approach as it has extensive documentation along with being the center of numerous works on the subject of procedural audio despite its spartan appearance. (Farnell, 2010) 

Later as the project continued however, the use of Pure Data instead was specifically used for the creation of more ambient or synthetic sounds; the humming of a computer console, the hissing of steam etc. The more procedural elements of sound design instead were going to be handled by FMOD.

FMOD is a audio middleware used in Game Development. It has been used by numerous games, both Triple A games such as; Quake Champions, Rise of the Tomb Raider, Starcraft II and Dead Rising as well as Indie hits such as; Celeste, Banner Saga 3 and Subnautica.

FMOD allows for the modification of sound at runtime both through randomisation and through giving it specific in-game parameters.

Within the Thinking City, one of the sounds that are altered during runtime is the footsteps of our enemy character. Each foot is made of different material and has a different selection of sounds to choose from based on that material. When the sound event is played, it selects one of these instances and plays it, but additionally, it also pitches the sound slightly up or down each time within a given range through our Audio Engine FMOD, this helps make what could end up being a very repetitive sound much less repetitive.

Farnell, Andy. (2007). An introduction to procedural audio and its application in computer games. 

https://www.researchgate.net/publication/253200017_An_introduction_to_procedural_audio_and_its_application_in_computer_games

 Fournel, N. (2010). Procedural Audio for Video Games: Are we there yet?. [online] Gdcvault.com. Available at: https://www.gdcvault.com/play/1012645/Procedural-Audio-for-Video-Games .

Andy Farnell 2010, Designing Sound, The MIT Press,