Game Development Reference
In-Depth Information
compatibility issues, research will be required to keep up on the latest
developments.
3D Sound in Games
We mentioned just earlier that middleware can assist in helping to
realize sound in three dimensions. 3D is now very commonly used and
available in a variety of game engines today, and helps to submerge the
player ever deeper into virtual worlds by adding more realism to game
environments.
Various technologies are used to emulate sound behavior in this
“real” world. Middleware audio engines help to provide the complex
mathematical programming needed to simulate this real world
phenomenon that we call hearing. Let's take a quick look and bring
you up to speed on some basic concepts in creating 3D audio for
games.
Positioning
Everyone perceives sounds dif erently. A sound card can emulate the
position of a sound source with HRTF on two speakers or headphones.
This function accurately models sound perception with two ears to
determine positions of the source in space, also frequently referred
to as a binaural coni guration. Binaural microphones and recording
setups usually use some kind of obstacle like a disc,
or more commonly a sphere or a model of a head—
or in some cases a person simply wears them like
headphones. This is because our head and body are
actually obstacles modifying the sounds we hear.
This is an important fact—depending on where
the sound is traveling from, it will reach one ear
faster than the other, and this is generally how we
perceive stereo in the real world.
In a multi-speaker system, such as surround sound,
(4.1, 5.1 or 7.1) the sound is distributed among
speakers that are located around the listener's
head. The sound coming from each speaker is
positioned so that the listener can locate it. In
principle, a normal panning setup is sufficient.
This means there are several channels, depending
on the number of speakers involved, which play
simultaneously on all speakers but at different
volume levels.
The HRTF (Head-Related Transfer Function) models the way we hear
3D sounds. The head in this case blocks out some sound waves coming
from the other side. Each ear is like an independent omnidirectional
microphone, and any sound will travel dif erent distances within the
space, creating dif erent delay times for each ear. This results in more
realistic 3D sound placement.
