AMBISONICS
Known since the 70’s
when first coder/decoder
proposals showed up,
the Ambisonics sound
coding system is based
in an elegant mathematical
formulation where both
spatial and temporal
sound information is
coded into 4 vectors
– x, y, z, and
w (for 1st. order Ambisonics),
as if it were projected
onto cartesian axes.
Initially conceived
to register a real sound
field recorded by soundfield
microphones, this format
can be adequately adapted
to permit the computer
simulation and creation
of artificial sound
fields. To reproduce
the sound, the vectors
are accordingly transformed
in outputs for loudspeakers
distributed in a known
configuration around
the audition area. A
clear advantage of this
method is in its flexibility
to choose the number
of loudspeakers one
wants to use, and their
positions around the
audition area.
Ambisonics scheme
(both sound objects
and loudspeakers
have their location
in the space parameterized
by the system)
Wave Field Synthesis
The second format (Wave
Field Synthesis –
WFS) is more recent,
and is based on a more
computational complex
formulation involving
the physical modeling
of the sound waves propagation
in the environment,
and takes into consideration
a discretization of
the physical space of
the audition area.
In this technique the
main goal is to emulate
a wave front that would
be produced by real
sound objects in a specific
acoustic environment,
through the usage of
a densely distributed
loudspeaker array around
the audition area. An
advantage of this technique
is its higher tolerance
to more listeners inside
the audition area and
its capability to induce
the perception of sound
fields located on a
larger audition area,
including the possibility
of positioning objects
in the middle of the
area, around or among
the listeners, and formed
ahead of the loudspeakers.
The wave front synthesis
is a critical task,
and may implicate in
a high computational
cost, which we intend
to approach using cluster
computing, distributing
the computational tasks
and calculus associated
to the auralization
process over the nodes
of a computer cluster.
.
Wave Field Synthesis.
(left) sound source
behind the wall. (right)
sound source inside
the listening area.
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