Spatial Sound for Computer Games and Virtual Reality - Game Sound Technology and Player Interaction: Concepts and Developments - page 303

Figure 10. 10.2 enhanced surround sound. The ITU-R BS 775-1 standard for 5.1-surround is L, C, R,
LS, RS and one Sub. 10.2-surround expands this by adding an extra Sub, left and right elevated speak-
ers, back surround, wide left and wide right speakers. L = Left. C = Center. R = Right. LW = Left Wide.
RW = Right Wide. LH = Left Height. RH = Right Height. L Sub = Subwoofer Left Side. R Sub = Right
Subwoofer Right Side. LS = Left Surround. RS = Right Surround. BS = Back Surround

acoustic properties of surfaces as declared in
AcousticMaterial.
Perceptual Model (see Table 3): Version 1 of
the MPEG-4 standard only rendered spatial sound
based upon physical attributes, that is, geometric
properties. However, virtual and synthetic worlds
are not constrained by physical laws and proper-
ties: it became necessary to introduce a perceptual
equivalence of the physical model. To this end,
two new nodes were added in version 2 of MPEG-
4: PerceptualScene and PerceptualSound. Rault,
Emerit, Warusfel, and Jot (1998) highlighted the
merits of the perceptual approach in a document
to the MPEG group:

A first advantage we see in this concept is that
both the design and the control of MPEG4 Scenes
is more intuitive compared to the physical ap-
proach, and manipulating these parameters does
not require any particular skills in Acoustics. A
second advantage is that one can easily attribute
individual acoustical properties for each sound
present in a given virtual scene.

The principle elements of the perceptual model
are drawn from research undertaken by IRCAM's
Spatialisateur project, and additional features are
derived from Creative Lab's Environmental Audio
Extensions (EAX) and Microsoft's DirectSound