Asctually, I think Francis Rumsey's keynote
speech looks interesting, and I would be
interested to read members' comments on the abstryt below.
David
Spatial audio reconstructing reality or creating illusion? (Talk)
The history of spatial audio is essentially one
about the dichotomy between two opposing ideas.
There have been those who emphasised the accurate
capture and reconstruction of sound fields, and
those who simply wanted to make a pleasing and
convincing spatial illusion for the listener`s
entertainment. Just about every position in
between these extremes has also been taken at one
time or another. The fact remains that with only
two loudspeakers it is impossible to reconstruct
an accurate sound field, although a large number
of perceptually convincing cues can be delivered
if the listener is willing to remain fixed in one
location. As we move into an era where highly
accurate sound field synthesis is possible over a
wide listening area, using a large number of
loudspeakers, we might expect the gap between the
two extremes to be closing. Strangely, however,
we find that listeners do not always respond well
to the sound quality and spatial characteristics
of systems that, on the face of it, ought to come
closer to reconstructing accurate sound fields.
Listeners can prefer less accurate systems. What
is going on here? Could it be that the inherent
impossibility of reconstructing accurate sound
fields with loudspeakers (because of spatial
aliasing, loudspeaker directivity, spacing, room
acoustics and other problems) means that even the
best approaches will risk creating perceptual
results that lie in the "uncanny valley" known in
computer animation. This so-called uncanny valley
represents a dip in the human cognitive
acceptance that leads one to consider as
"unnatural" any form of synthetic creation that
comes close to being like the "real thing", but
does not achieve complete accuracy. We humans
suspect things that are almost real (but not
quite) of being "weird" or unusual (the zombie,
the prosthetic hand). When the artificial
reconstruction gets close to the believability
threshold, a different group of cognitive
responses possibly comes into play. Whereas the
limited perceptual cues arising from two-channel
stereophony or even 5.1 surround could be
accepted by the brain as something far enough
from reality to be dismissed as artificial, and
thus enjoyed for their own sake, perhaps the more
scientifically accurate systems possible today
give rise to a different set of human critical
faculties that say something like "it sounds like
it ought to be real, but something is strange".
Perhaps I am wrong, though, and it is simply that
the undesirable artefacts or side effects of
inadequate sound field reconstruction are simply
more unpleasant than those arising from simpler
spatial audio systems. Can we cross this
complexity threshold successfully, and do we want or need to?
Francis Rumsey
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