On 2012-10-03, Eric Carmichel wrote:
In nearly all Ambisonic setups, the listener's head lies on a line
connecting two or more speakers.
The classical regular pantophonic decoders make no such assumption, and
work just fine. For your purposes, of the five Platonic solids
unfortunately the only one not having the property is the tetrahedron,
which we already know doesn't work for ambisonic purposes. More
irregular spacing do work just fine, it's just that they're not that
easy to analyze (you usually don't get a neat Gaussian quadrature
formula of the kind which helped Gerzon in his development of the
SoundField mic) and they will rarely yield results as near to the
optimum suggested by the number of speakers and a fixed, uniform array
diameter.
The "Ambiophonic" component would be using dividers (gobos or flats,
as they're called) between speakers so as to reduce early reflections
in an otherwise "standard" living room space.
That makes no difference as long as the flats really are absorbant
enough. They rarely are, though, so my expectation would be that they do
more harm than good. Especially since any reflections off them would
very closely spaced with the direct sound, leading to combing and
whatnot. That doesn't happen as discretely with farther off, more
irregular absorbers and diffusers.
A forward ambiodipole is a different thing altogether. It's so close to
the flaps that the effect doesn't matter. (Any possible frequency domain
ripples are so high in frequency and any temporal domain effects
conversely so close to each other that we don't perceive them.)
At the most general level, I'd say it makes sense to introduce a spatial
anisotropy into the field with a stationary listener who has two ears,
and thus a perceptual anisotropy himself. That's what the frontal (and
perhaps backwards, up, whathaveyou) flap does within ambiophonics. At
the same time it does *not* make much sense to introduce further
anisotropies along other axes.
From what I've read about Ambiophonics, it's an extension of
transaural stereo techniques (e.g. William Gardner's doctoral thesis)
with the addition of a partition.
Correct, though it's a far more refined and scalable version of it.
It seems that the advantages provided by the partition (or partitions
in my case) would apply to Ambisonics.
http://www.ambiophonics.org/files/AES24Banff_1.html
The two systems can work in tandem, but I don't think they can be melded
into one. At least not without head tracking, which is a rare commodity.
Ambisonic is a psychoacoustically assisted field reproduction technique,
while ambiophonics is fundamentally founded on binaural/transaural ones.
They don't exactly go by the same rules.
--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-50-5756111, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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