On 01/07/2011 11:35 PM, Niels Mayer wrote:
On Fri, Jan 7, 2011 at 1:29 PM, Paul Davis<paul@xxxxxxxxxxxxxxxxxxxxx> wrote:
ambisonics assumes a speaker in the midst of an array of speakers that
point more or less in the general direction of
the listener's head. this phone is just a gimmick.
if you're interested in beamforming with spherical speakers, check out
franz zotter's and andy schmeder's papers. executive summary: it can be
done, but it requires quite some oomph if you want to cover more than
just one or two octaves. implementing this on a cell phone will always
remain a marketing gimmick without any real value.
If that is true, then I guess the link I posted regarding
CNMAT/MeyerSound "eigenspeaker" is bunk?
no, it's not. that's andy schmeder's project i was talking about. it
does work, but it's not really about surround sound (unless you happen
to know your room exactly, in which case you can bouce beams off of
walls and get some sort of surround effect, but with huge artefacts and
sidelobes).
these speakers are for acoustic measurements and simulation of radiation
patterns. you could for instance sample a violin with a sphere of
microphones, and use one of these spherical speakers to create something
that looks like a violin and quacks like a violin.
I'm talking about a different configuration of ambisonics than the
traditional speakers around the listener and the associated sweet
spot. IMHO that's a somewhat difficult configuration, especially for
mobile apps, so I was just wondering whether the effect be gained with
only four speakers in a "polar" configuration.
you can shoehorn ambisonics theory into this "inside out" application.
dylan menzies (and maybe dave malham, too) has formulated this idea some
years ago and called it "o-format". but it's not generally useful.
And if not four, six, eight, or how many? Can they be arranged in a
"circle" around the perimeter or is 360 degree configuration of
drivers required?
you can do circular beamforming, but it will be even less effective than
spherical. think huge amounts of destructive interference and ugly, ugly
side lobes. for beamformed bass, you need ridiculously long coil travel
and loooots of power.
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