['Ducking', or lowering the audioscape volume, can create greater engagement for listeners, and Day 1's Quarles explains how it's done in this fascinating game audio feature.]
When watching a big action scene in an adrenaline-fueled summer blockbuster, a viewer is bombarded with lights, quick camera cuts, explosion sounds, a pulse-rattling score, and a hero that often mutters a snarky one-liner before sending the primary antagonist into the depths from whence he/she/it came.
As someone in the audio field watches the scene, they automatically peel the sequence apart layer by layer. You have the musical score, the hundreds of sound effects playing at once, the dialogue track, and on top of all that, you have a gigantic mix that must be handled elegantly and intelligently so the viewer understands what is happening onscreen and does not go deaf in the process.
There are multiple techniques in a post-production environment that are often used in tandem when pushing towards the final mix. Methods such as side-chain compression and notch EQ play very important roles in film and television, but they are a linear/time-locked medium.
Since the video game medium is interactive in nature, you cannot always predict where a player will go and thus, how a sound will be played (and heard) in the game world. Couple these issues with real-time effects being utilized (reverb, distance-based echo, low-pass, etc.) and it can be very difficult to lock down exactly where the audio spectrum is at any given time.
One important technique that audio professionals oftentimes employ to great effect is one that is called "ducking." Ducking, at base level, is essentially the practice of discreetly lowering the volume of all elements of the audioscape with the exception of the dialogue track. This allows more headroom in the final mix, which will provide important information to the listener that may otherwise be missed due to the complexity of what is going on within the soundtrack at that particular moment.
To understand the validity of a process such as ducking, certain elements must be taken into account beforehand. First and foremost on this list is game pace. Game pacing is a basic game design practice. It is essentially the approach of creating a gameplay experience that has multiple peaks and valleys in the action so the player does not become fatigued and disinterested in the product.
Audio plays a key role in effective game pacing. The reason is simple; the vast majority of elements in a game have an aural representation, and if the gameplay action and visual portion of a product is relentless for too long, the audio spectrum will lose dynamics and quickly become a wall of noise. When this happens, the player will more than likely turn down or mute the audio -- thereby destroying the atmosphere and the pacing that the developers were trying to achieve.
Fortunately, there are a number of ways in which a development team can avoid this problem. In an ideal scenario, the audio team would be involved with all level layout meetings and planning discussions to help with audio pacing through the game.
Much like a great piece of music, a game has a "rhythm." It has establishing motifs and themes, it has gradual builds and rising action, it has massive climaxes, it has denouements, and it has resolves. If it's a constant climax, the player will get exhausted and probably pretty frustrated after awhile.
In addition, as a project gets closer and closer to final lock-down, the more important it becomes that the audio department is aware of any changes that occur at the design level. For example, if a new battle encounter is added to a section of the game where there wasn't one before, the "rhythm" of the level has now changed.
The audio department needs to be able to go through the levels and do a final mix of the entire game from top to bottom after design has completed any major reworks to make sure that the aural integrity remains intact throughout the shipping process.