Information Technology Reference
In-Depth Information
Figure 9. Sound node hierarchy in the Java 3D specification
The Doppler effect is achieved by taking the
value of the speed of sound, multiplying it by
the velocity scale factor (which is the change of
speed relative to the listener's position) and then
proportionally applying the frequency scale val-
ues. If the velocity scale factor is 0.0, no Doppler
effect is processed.
For further information on the Java 3D
API the reader is referred to Murphy (1999a),
Murphy(1999b), Murphy and Rumsey (2001),
and Murphy and Pitt (2001).
console) . In relation to the current mass-market,
5.1 channel sound is the standard deployment
for multichannel sound output. This consists of
a left, center, right, left surround, right surround
(5) and Low-Frequency Enhancement (.1). 7.1
sound is also popular and 10.2 (see figure 10) is
the emerging next generation of surround speaker
setup. Work is also being done on 22.2-surround
sound. Games generally follow either a 2.0 (stereo)
or 5.1-channel standard.
5.1-surround sound is effective to a point.
However, it is essentially a coarse representation
of the spatial sound field. Stepping between the
speakers, as sound moves dynamically from
frontal speakers to surrounds, can be quite audible.
A natural sound (that emanates directly from an
acoustic sound source and not via speakers) retains
its timbral characteristics despite colouration from
XNA/XACT Implementation
of Surround Sound
XNA/XACT is a collection of game develop-
ment technologies produced by Microsoft for the
various Windows platforms (including the Xbox
Table 1. AuralAttribute Object Properties
Parameter
Default Value
attributeGain
1.0
rolloff
1.0
reflectionCoeff
0.0
reverbDelay
0.0
reverbBounds
null
reverbOrder
0
distanceFilter
null
frequencyScaleFactor
1.0
velocityScaleFactor
1
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