Audible Immersion

Sound plays a major role in video games. That is why the audio team here at Firearms: Source (FAS) is extremely passionate about producing a quality audio experience for your enjoyment. We believe that the sound in a video game should represent physical reality for the purpose of realism, but also allow for creative artistic expression. Firearms: Source strives to be a source of realistic weapon functionality in electronic interactive art, and it is the mission of the audio team to have FAS sound accurate and detailed as well.

Our approach to sound design in FAS is evolving as production progresses. Our primary focus on the games sound design is to elicit an emotion of great satisfaction as the players pop off shots. An in-game gun battle should bring to your subconscious mind a sense that these things will kill shit. It’s crucial that we tailor the waveforms in such a way that strikes those chords.

Firstly we’re going to take a look at what’s planned for version 2.0, then we’ll dive into the technical aspects of how we refined our work. The atmosphere of FAS 1.0 was extremely quiet in terms of ambient sound; there was barely any action in the background. For 2.0, we actually have ambient battles taking place, even if the map just started, giving the player’s mind the perception that things are happening. Now we understand there’s a delicate balance to this, so be aware that we don’t want to deafen players from ambient jargon, no. We simply want to keep the player immersed in the battle experience and bring about a sense of a wartime environment.

FAS 2.0 takes the maps and brings them to life by adding locational sound, like air conditioners, fires, buzz and hum from improperly wired circuitry, etc. We want these things to “pan” across the player’s speakers as you pass them by, to give a sonic reference to where things are to accompany the visual aspects. This is by no means revolutionary technology, but it’s important that we do bring this dimension to the experience for that extra immersive kick. For an interesting in-depth look at soundscapes (the Source Engines audible environment) read Acoustic Ecologies: Half-Life 2’s City 17 by Michel McBride-Charpentier. Michel shows you how big of a role sound plays in telling the story of a level.

Gunshot sounds in 2.0 just picked up a berzerker pack. We’ve jacked them up almost an additional 6 dB in volume. Extra care has been brought to these sounds with the addition of a new technique to creating more of a punch. One observation about version 1.0’s way of making gunshots was that the sound was a bit quiet and weak. This was because gunshots began with the most intensity in the beginning and then gradually decreased to silence. Seems normal. Well 2.0 goes a step further and takes into strong consideration the cycle time of automatic weapons. The time in which a gunshot repeats (in milliseconds) is marked in the audio software as the gunshot is created. Still the most intensity is in the beginning of the shot, but it quickly descends in volume around 6-9dB as we reach the marking of the cycle time. Then after the cycle time, the volume is brought back up in intensity to almost the same level as the beginning, where from there it begins to gradually decrease to silence. Take a look at this graph for a better illustration of what the waveform looks like in this example.


Why do this? Well on single fire, the gunshot sounds like a whip-crack, instead of just a crack. You hear a slight delay before the beginning of the echo, and that really helps you to feel like you’re in a reverberant environment. On automatic, this helps tremendously in letting the intense gunshots breathe a bit. What’s perceived from that is a sense of space. This lets us make the initial pop of the gunshots louder than normal, while allowing on automatic fire for this pop to remain at a comfortable level, without distortion. Keep in mind, since 1.0, our gunshots overlapped each other. Never had they acted in a monophonic sense, such as once the next gunshot is played, the previous one becomes cut out. Next time you’re in-game, turn cheats on with “sv_cheats 1″ and type “snd_show 1″ into the console and start shooting. You’ll notice in the text readout that multiple gunshots are overlapping and mixing with each other, just like Left4Dead.
In terms of making the gunshots sound different, we took a realistic/artistic approach to this. What makes a gun sound the way it does is really determined by three major factors. First the caliber and amount of powder, second the length of the barrel, and finally the environment in which it’s fired in. We kept in mind that a weapon of similar caliber with a shorter barrel generally has a louder sound, higher in pitch. Longer barrels generally are lower in pitch and actually not as loud. Now this isn’t our guide that determines all we do, but we use physical reality as an inspiration to where we take the general direction of the sounds. We still enjoy letting our creativity flow without hardcore restrictions, otherwise literally everything would sound too similar. For a good example of how the unique environment plays a role in the sound timbre (its unique tone), check out a few videos on Hickok45′s YouTube Channel. He’s very knowledgeable and to me quite entertaining, but at the same time you’ll notice how almost every gun sounds extremely similar due to the environment.

For us to give the weapons different personality, we needed to change some qualities about each gunshot, such as: differences in echos like the ammount of distinct reflections, dominant frequencies in the explosion of the round, and clarity of phase in the initial shot. When mixing multiple sounds together to create an entirely new sound, it’s very important that we align the frequencies in the beginning of the wave as best as we can to allow for the most clarity. A good example of phase alignment can be seen in this following example. This over dramatized example shows you how making the strongest sounding punch occurs when you have as many waves aligned as close to eachother as possible. The result is additive.

out-of-phase in-phase

(Left: Out of Phase; Right: In Phase)

In version 2.0 we now included properly implemented distant gunshot sounds. The Source Engine allows us to use a stereo wav file as both the close up sound (the left channel) and as a distant sound (the right channel). After the player hears a sound beyond the engines pre determined range, the engine will mix volumes between the left and right channel and give us the effect of distance as players shoot from afar. The difference this makes from not having this to having this is remarkable. A whole new dimension is added to the gameplay where you now have a great sense of how far someone may be when they’re shooting. You’r probably familiar with this if you’ve played Day Of Defeat: Source. Having this in the game means that we need to create a new sound for the distance versions, so to do this we duplicate the close up sound and begin to use a series of effects to create that sound. Starting with a shelf equalization boost of 6dB at 5000Hz brings that neccessary air to the sound. Next passing the audio through a wah-wah filter with the center frequency set to 1,000Hz with our depth percentage at 50% and our resonance percentage at 50% somehow does just the right job at giving the audible illusion of distance. Combine that with a serious amount of amplitude compression (it varies for each sound) and you have a very detailed distance sound. For best results, if you happen to mix sounds with multiple tracks, you can select which individual tracks will have these effects applied to them and which ones stay the same. Finding the right mix will allow for the explosion of the round to have the highest frequencies, while the decaying echo sounds mostly distant and filtered.

FAS 2.0 Sound Preview – Mod DB (Old, 2011)

On behalf of our sound designers “Engineer” and myself “Vunsunta”, we want to thank you for reading what’s been going on in our part of the world here. We’ll sign off with an mp3 of some sample audio planned for 2.0. Have fun reading our upcoming blogs of behind the scenes goodies from other members of the team!