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Immersive
Audio for Complete Virtual
Reality
VR systems where the
auditory experience
is matched to the visual
experience are considered
as complete virtual
reality ones. If the
VR environment is immersive,
as occurs in the Digital
Cave where users
are immersed inside
a virtual scenario and
have freedom to move
around, the experience
of complete (audio and
video) virtual reality
is also said immersive.
Imagine yourself moving
around exotic musical
instruments playing
in an ancient greek
arena, or the experience
of creating personal
orchestras and listen
to them not from the
auditorium, but immersed
in the scene, surrounding
the instruments. Virtual
audiovisual experiences
like this could be explored
and made feasible by
means of complete immersive
VR, in environments
such as the Digital
Cave.
Most previous virtual
reality systems, in
special those said immersive,
do not possess an efficient
mechanism for auralization
and sound projection
in the space, capable
to allow the creation
(or the recreation)
of a realistic sound
field in the 3D space.
This necessity led to
the first applications
segment of this project,
directed towards the
investigation and production
of solutions for sound
equipment in virtual
reality.
In technologies for
VR and computer graphics,
the virtual environment
simulation has, per
many years, given priority
to the production of
the scene visual experience,
and to the improvement
of its qualitative aspects
(texture, resolution,
and feeling of depth).
Technical problems in
this context approach
issues as numbers of
polygons, textures rendering,
pixels and voxels oriented
processing, algorithms
for ray tracing, and
others addressing the
visualization task.
In respect to the sound,
the sound projection
in the space corresponds
to the auralization,
a more general terminology
which extends the concept
of previously used terminologies:
for many years the data
sonification and
the sound spatialization
had been more common
terminologies in virtual
reality applications.
It is desirable that
the auralization system
be based on loudspeaker
(multichannel) paradigm
so as to provide wider
mobility and freedom
for the users, who wouldn’t
need headphones. However,
the creation of three-dimensional
sound fields mathematically
and/or physically correct
is a complex task, which
has gained a lot attention
from the scientific
community in the last
years, being currently
a research field very
active and promising,
specially after the
considerable growth
of interest due to the
popularization of the
surround systems for
cinema (movies) and
home-theaters, known
as 5.1.
5.1 and 7.1 systems
(standard ITU-R BS.775)
There are several ways
to develop sound spatialization
solutions or auralization.
Systems, as a whole,
encompass from the design
and development of the
audio infrastructure
and equipment installation,
to the conception and
design of applications
for navigation in the
3D environment, the
acoustic scene composition
and control, and the
choice and implementation
of 3D audio coding formats,
which could be several
too.
In VR advanced applications,
the CAVE-like environments
are particularly the
ones that more benefit
from auralization techniques,
i.e., of the emulation
of a three-dimensional
real sound field of
one given audiovisual
scene, either through
loudspeakers or even
using earphones, so
as to allow the real
sensation of the immersion
in the virtual environment,
and to guarantee the
coupling of the 3D visual
perception with the
3D auditory perception.
The first AUDIENCE
system addressed this
demand, making possible
a system for 3D sound
field production surrounding
the users, and giving
life to a sound scene
written in a scene description
language (e.g., X3D).
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