In this reprint from the April 2007 issue of Game Developer magazine, guest contributor Rob Bridgett invites sound designers to think about how they can enrich the ambient sound of their games. Ambience is an often undervalued area of video game sound. It's the canvas upon which all the spot effects, dialogue, and music sit, but it also has a much more powerful interactive potential. Ambience typically tends to be loops of one or two minutes in duration, which is generally inactive and doesn't draw any attention to itself. This makes good sense in games that have very predictable setpieces in terms of gameplay and have minimal dynamics to their play narrative. However, as we enter a new era in video games, particularly in cinematic consolebased games, where action sequences are balanced with periods of relative calm and exploration and where interactivity with more or less any object or character in a game is possible, there's a clear opportunity to make ambience more detailed and involved.

Art of Immersion

Ambience generally hints at a world just outside what can be seen and experienced on screen. It performs the functional task of making a scene feel real and continuous, no matter what other effects are layered on top of it. Everything should seem to belong to the same scene. It doesn't have the in-sync immediacy of sounds that are coming from within the on-screen diegesis. This is not to say that it cannot represent and reflect events that are occurring as a result of gameplay actions the player has undertaken. The sound of distant sirens in a large urban setting, for example, may indicate that tension has slowly been raised, either because of actions taken by the player (for example, shooting) or because something has happened in the game world that will soon become apparent. These sounds are not merely there to add flavor or a mood to the game, although they can clearly do that very well. What differentiates ambience in interactive entertainment from ambience in film is that it's reactive to events. I tend to think of interactive ambience as musical score. It has a powerful subliminal effect on the player and raises or diffuses tension in a very subtle way. When it reflects events that the player is inaugurating, the effect is very powerful. This works especially well when orchestrated along with all the other elements of an interactive soundtrack such as music and spot effects. The idea that interactive events are being triggered by a kind of ripple effect in the distance is indispensable for immersing the player further into an interactive world. It gives a great impression of life beyond what’s happening directly on screen and helps to fill the player’s head with notions of an unseen and reactive world that isn’t being rendered by the game engine, but by the player’s imagination. The crowd ambience in sports games has long been interactive to events that take place at run-time within the gameplay narrative. Here, various crowd reactions are reacting directly to what occurs -- they’re not simply a continuous crowd loop that occasionally feels right. It's this use of ambience that can be extended greatly into other genres, such as open world crime and first-person shooters. Rather than having a bed of sounds that accidentally works every now and then, there's a membrane of interactive ambience that feels organic and responds to user actions telling a more subtle and subliminal version of the story as it unfolds.

Record on Location

It can be highly beneficial to a project’s audio if, as a sound designer on a project set in a real world location, such as Miami or Cuba, you have the opportunity to travel to those areas and make location recordings of the ambience. Unlike film productions, video games have no equivalent to being on location and collecting location sound. A visit to the location will give you not only the opportunity to collect real sounds, but also a genuine feel for the environment. In sci-fi or fantasy projects, ambience still functions to create the feel of the world, perhaps more so than a real location. And although it's impossible to collect "authentic" sci-fi ambient sounds, it is possible to find locations that have a similar feel as what you're trying to create. For example, the sounds in a stark abandoned building may provide lots of inspiration and source material that can be processed and adapted toward a forlorn alien planet game world.

Can It Be Captured?

When you return to the studio, you may find that the sounds you collected really don't give the same impression as when you were there. Bear in mind that sound is not only heard, but also physically felt (especially in very loud locations, such as New York City) and influenced perceptually by everything else in the environment, from temperature to heat to smells and visual cues. All these factors greatly affect what how the brain processes sound, which is why it's very important to capture the whole feeling of a place and not just the sounds being emitted. Taking photographs at each location will help you catalogue and recapture the feeling back in the studio. You might choose to sweeten the recordings with additional sounds in order to better replicate the whole feel. There are many factors that affect the noises of a particular location; these sounds are quite different from what most of us hear in our every day environments. To create authentic sounds for a game, it's essential to visit real locations that reflect the game environment to capture and reproduce these local quirks.