Game Development Reference
In-Depth Information
ambient sound
Ambient sound systems help to breathe life into projects. These are the gusts of
wind heard blowing in the background, falling rain, crickets in the marsh, and
the patter of feet from people walking past your character on the street. Because
many games are nonlinear, the audio can't necessarily progress in one set path.
If the character turns and goes back the way they came, then the audio needs to
reflect that. Again, the more overlapping or layered these sounds are, the more
immersive a game can become.
To create effective sound for nonlinear games, most audio is created in short
loops, about 5-30 seconds long, that can be triggered by the game engine
depending on factors such as
Physically where the player is in the world
What the player is doing
Circumstances such as events or other characters the player
encounters
In the simplest of games, the ambient soundscape can be described as utilizing
a variety of steady loops creating the overall tone of the setting (such as the steady
dripping of leaky pipes in a sewer system), as well as one-shots (the occasional
rat scurrying by, or a distant pipe creaking). Multiple files of one-shots can be
created and played randomly throughout a game, instead of being specifically
triggered by locations or events. This randomness also plays an important part
in breathing life into the game and avoiding too much repetition, which can
become boring in long games.
sampling
Sampling, referred to in audio production as the sampling rate , is the number
of samples per second required to digitize a specific sound.
Figure 8.4 shows two sampling rates for the same audio signal. The audio sig-
nal is a 1 kilohertz (kHz) sine wave (a fairly common signal used for calibrating
audio hardware and software). The screenshots of the different sample rates were
taken while these audio files were opened using a program called iZotope RX
( www.izotope.com/products/audio/rx/ ).
The little white square dots that occur along the waveform in each image mark
where the audio signal was sampled (to put it in visual terms, it's the same prin-
ciple of frames per second that is used when discussing film/video: the aperture
closing and taking a snapshot of an image in time).
the sampling rate
determines the
sound frequency
range and is usually
viewed as a wave-
form. this wave-
form is frequently
referred to as its
bandwidth .
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