Ambience in the levels act as a base layer of audio, providing location-based sound for when the gunfire falls silent. The wind, birds, and rivers are low in the mix and usually masked by weapon fire, but without it the gameplay area would feel empty and unnatural.
The fun part about game audio is that no matter how realistic you try to make it, it is always entirely fake. Unlike with film where you return to the edit room with some audio from the shooting location, the silent game world is the audio equivalent of a blank canvas. You can apply anything you want as the level ambience, provided it makes sense to the project! In our Pegasus Bridge map for example I use several main wind recordings, mixed with localised bird chirps and rustling trees. The ambience sounds different in each part of the map and you can hear the changes as you are running through it.
While we don’t use a dynamic time cycle in our maps, it was important to create a setup that would cater for it anyway. This means the two different times of day for each of our maps are able to have distinct ambiences that can change just as easily as the lighting, without requiring multiple triggers or map layers.
There is a lot more to weapon audio than the simple ‘bang’. You want to be able to hear the weapon fire, the casing drop to the floor, the bullet impact, the echo around the landscape, and then the bullets from the enemy whizzing past you as they return fire. It is with all of these stems working together that you get close to the intensity that the game requires.
The bullet impacts are some of the most aggressive sound effects in the game; I wanted every individual bullet to be noticed whether it hits you or not. If you are taking cover behind a crate then expect to hear the wood splinter and crack in front of you. Similarly, hiding behind a car or the metal structure of Pegasus Bridge will cause loud metallic pings to ring out around you, and if a bullet flies past you will hear the ‘swish’ as it whizzes over your head. When this is combined with the visual suppression effect it heavily affects your ability to pinpoint your attacker, and when all of this is combined with our HRTF-based 3D audio, gunfights can be a very tense experience!
I set out with an aim to have as much of the ingame audio created by the players as possible. I didn’t want an overly complex atmosphere, instead preferring a focused yet understandably hectic audio mix. I wanted the gunfights and explosions to be harsh and disorienting, but most importantly to be influenced by their real-world characteristics. This is why you can hear every weapon in the game from no matter where it is fired. I have spent far too many hours creating and refining a complex filter system, along with intricate crossfading to make each weapon sound as you would expect it to at 10 meters, 50 meters, and 200 meters distance. This has been time consuming and the parameters are constantly being tweaked as the mix changes, but the outcome is a very dynamic and responsive battleground. I’ve even added a delay that increases with distance, so at range you will see the explosion before you hear it, modeling the speed of sound.
Just like many aspects of the game, the audio is constantly being tweaked and adjusted, and will continue to be refined up to release. Obviously there are many audio requirements that have not been mentioned here, but the weapon audio system has been a large project in itself and thankfully it’s easy enough to expand to additional firearms and equipment in the future.