On 12/7/21 2:15 PM, Sampo Syreeni wrote:
On 2021-12-02, eric benjamin wrote:
I believe that Nando may have been thinking about reproduction with
loudspeaker arrays. He has a system with eight loudspeakers on the
horizontal plane, as do I. So good up to third order.
And I actually have access to a 56.8 system[*] (in our "Stage" small
concert hall), the main horizontal speaker ring is 20 speakers, so quite
a bit more potential spatial resolution than just 3rd order.
What is interesting here, to me, is that sampling on the recording side,
and reconstruction on the playback side by discrete speakers -- also an
instance of sampling in space -- are not the same, and they deteriorate
the reconstruction of the soundfield separately. Sampling in recording
array and sampling in reconstruction array...I've never really seen them
analyzed at the same time, in the same framework. It's always been so
that we go to an intermediate domain, which is continuous, with a little
bit of wobble angularly, in noise or gain figures, and then back the
same way.
It's all whole and good, if you can assume independence in all of the
errors on the way. But then, you can't: the above Swedish case which
I've been arguing, *certainly* doesn't admit such symmetry or
independence assumptions.
Yes, there will be errors created by both the capture process (encoding
into ambisonics), and by the imperfections of the playback environment,
be it binaural or plain old speaker arrays. The errors will be mixed
together...
So, the statistical asummptions which underlie e.g. Makita theory, and
there Gerzon's, don't go through. In particular, since we're dealing
with wave phenomena, there is interference to be contended with. That
doesn't come through at *all* in statistical analysis, across 2D and 3D
analyses; 3D coupling to a 2D sensor is *wildly* uneven, and if you have
a box around the sensor, it can be shown that the sensor coupled with
its idealized surroundings, can exhibit resonant modes which run off to
an infinite degree, within an infinitely small degree, in angle. It will
*always* be nasty, at the edge.
But I actually have 24 full-range loudspeakers available. Would it be
advantageous to expand our systems to higher order?
When you have those, the next thing is, you need an anechoic chamber,
and well-calibrated microphones. I mean, you have the machinery to
launch physical signals, in 3D. Now you need measurement machinery to
catch what you launched, and a silent space between which doesn't
perturb your signals. Is it that not so? ;)
Yup. While an ideal environment is best, we can try to do some testing
done in less than ideal circumstances. Let's assume we have some
"machinery" in place (reasonable playback environment, reasonable
capture tools).
The question (to me) is really: what do we actually measure once we have
the machinery in place? Are there objective criteria that can tell us
what is perceptually relevant?
I would love to have the original 7th order recording that started this
thread, so that it could be played in different systems and with
different orders (Jens?).
Or: we can build horizontal arrays (or 3d arrays, for that matter) with
N capsules, where N is an ever increasing number.
What is the number of capsules and encoded order at which it does not
make sense to keep adding capsules (and spherical harmonic components).
What is the point at which "the incremental perceptual improvement, if
any, is very small and does not justify increasing the number of
capsules needed to capture higher orders". I know this would not be a
black and white hard limit, of course...
-- Fernando
[*] https://ccrma.stanford.edu/~nando/publications/stage_grail_2019.pdf
_______________________________________________
Sursound mailing list
Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit
account or options, view archives and so on.
