Fernando Lopez-Lezcano wrote:
It is a bit frustrating to read about (probably) interesting projects
which are< completely unintroduced >.
https://ccrma.stanford.edu/search/node/Octathingy
Didn't find any real info. Is this supposed to be some 2D design? If so,
Orange Research Labs also had some prototype, and also some 12-capsule
(2nd order-3D) prototype but which seems to be to big. (Capsule
distances on sphere implied an spatial aliasing limit of about 4.5kHz,
which would be (too) low for any serious recording.)
So, < before > talking about 3D printed holders: What actually IS an
8-capsule Octathingy?
Sorry about that, yes, the Octathingy is the informal name and it
would not be found by a search. As I say, there is a LOT of
documentation missing from the pages. I will slowly fix that, thanks
for pointing this one out!
Waiting for some enlightening infos... :-)
I have to add a link and/or the pdf of the paper. Look for the AES
Audio Engineering Society Convention Paper 8728 (2012) by Eric
Benjamin, "A second-order soundfield microphone with improved polar
pattern shape"... the abstract says:
"The soundfield microphone is a compact tetrahedral array of four
figure-of-eight microphones yielding four coincident virtual
microphones; one omnidirectional and three orthogonal pressure
gradient microphones. As described by Gerzon, above a limiting
frequency approximated by f c = πc/r, the virtual microphones become
progressively contaminated by higher-order spherical harmonics. To
improve the high-frequency performance, either the array size must be
substantially reduced or a new array geometry must be found. In the
present work an array having nominally octahedral geometry is
described. It samples the spherical harmonics in a natural way and
yields horizontal virtual microphones up to second order having
excellent horizontal polar patterns up to 20 kHz."
The capsules are located in the vertices of a square antiprism...
(the reference is also in the paper about the project that I have in
my home page)
Best,
-- Fernando
Thank you very much for providing these detailed and useful pieces of
informations!
Best,
Stefan
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