
Mics that record in 3D ambisonics are the next big thing - glitcher
http://cdm.link/2018/09/3d-ambisonic-microphones/
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MrRadar
Ambisonics is a fascinating technology. It's basically the same concept as
differential stereo encoding (where you record an R+L and R-L channel and use
them to derive R and L, or just play the R+L channel for mono) extended to all
three axis to create surround sound (so you have a sum channel, a horizontal
difference channel, a vertical difference channel, and a depth difference
channel). This was all developed in the 70s (and thus out of patent today) but
abandoned for more direct means of encoding surround since it was more complex
to process the signals for not much gain. Of course now with DSPs the signal
processing is much easier and with VR there's suddenly a niche for it to fill
since it fully preserves the 3D soundscape (unlike e.g. 7.1 surround which
only records 7 point sources at fixed positions).

On a side note, the upcoming 1.3 release of the Opus codec is adding support
for Ambisonics-encoded surround sound.

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jayd16
This would only be 3 axis sound right? I don't think you can get full 6 axis
reproduction with this, can you?

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acjohnson55
What do you mean 6-axis? We're talking about directional pressure at a point,
so 3 dimensions is sufficient.

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jayd16
6-axis as in not just directional, but positional. You can both be looking
towards or away from a source, as well as looking forward but moving your
listening position in such a way that the source is either on the left or
right side of listener. In full roomscale VR you'll ideally want to handle
positional tracking as well.

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wdfx
I actually built two of my own 1st-order ambisonic mics and the decoder
plugins about 6 years ago. I shelved the project since I couldn't (and still
cannot) afford a playback system beyond stereo :(

It was pretty cool to rotate the soundfield through headphone playback to have
the recorded audio whizzing around your head :)

I never thought at the time that VR would become popular again and provide a
good use case for this technique.

~~~
fho
Been there, done that. Although mine is not finished yet :-)
[https://imgur.com/a/myBFYgU](https://imgur.com/a/myBFYgU)

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wdfx
haha, I built an almost identical tetrahedron for my first prototype with tiny
capsules :)

for the larger capsules I had to use more parts for the frame (small pieces of
bent brass) to correctly mount the capsules.

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anigbrowl
Audio professional here. Ambisonic recording is great, though it does have
limitations because you're baking in spatial information in a way that will
limit editing later - it's _not_ a magic bullet for location audio, although
it will be a valuable supplement.

If you're interested in getting into this, you can feel good about the Zoom
product. They deliver outstanding value for money. I've used them on several
feature films, first as backup recorders but later as the primary audio
capture platform.

~~~
wizardforhire
Audio professional here also! I too have used zooms as backup and as a primary
mixer. This comment is on point. I’d like to add that close mic-ing and
multitrack recording are never going away. Given that, it would be nice to
have high quality ambisonic microphones with inline dsp’s and post production
suites designed to handle the new spatial awareness. There needs to be a
standardazion for spatial audio information developed for cross compatibility
and a new UI design on the channels strips in the Daws to ease workflow. I’m
envisioning instead of a pan knob a trackball or trackpad would suffice.
Diving deeper, there could be channel programmable parameters to set room
size, aborbtion and reflection rates.

~~~
femto
If it's not off topic, what's your take, as a professional, on the value of a
single chip with the ability to record/playback several hundred channels? Are
these a readily available piece of kit, or are they not worth having?

I ask because as part of a student project we've demonstrated a delta-sigma
DAC on an FPGA with very good dynamic range. We should be able to put a lot of
these onto the one FPGA. It might also be extended to an ADC.

~~~
chaboud
As an audio professional, I think you’ll find some interest, but it will be
limited. Massive channel count can be useful in beam forming cases (e.g. Shure
MXA910 array ceiling panel) or spatialization/impulse-representation cases
(e.g. Meyer constellation).

I _do_ think that consumer mic array representation could be valuable
eventually, but you’re going to need to beat the costs of ADC’s and simple
multiplexed front ends. An FPGA is an expensive way to do that at volume
(think ASIC).

Consider per-channel gain stages for dynamic range enhancement...

~~~
femto
Thanks for the response. Good point on multiplexing, as fast high resolution
single/dual channel ADCs are now cheap. It will be interesting to look at how
much the multiplexing costs relative to FPGA (which can be quite cheap). At
this stage the circuit we have is mostly a curiosity, but it will be
interesting to experiment with it.

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michaelbuckbee
Marvel's new Wolverine podcast/radio play is recorded in ambisonic sound [1]
if anyone wants an easily accessible example.

Per the article:

The ambisonic mic necessitated a different method of recording the show.
Instead of the standard “one-person, one-mic” studio approach that the actors
recorded simultaneously, in the same room. The approach allowed for more
interaction between actors, more like staging a play than recording an
audiobook.

1 - [https://www.theverge.com/2018/5/30/17409704/wolverine-the-
lo...](https://www.theverge.com/2018/5/30/17409704/wolverine-the-long-night-
marvel-podcast-universe-interview-behind-the-scenes)

~~~
modernerd
It sounds great! Trailer at:
[https://www.wolverinepodcast.com/](https://www.wolverinepodcast.com/)

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jakobegger
I wonder how people play back those 3D recorded sounds?

If you want a 3D audio experience, it's possible to do that with just two
microphones and a dummy head model [1]. Then you just play back the recording
with earbuds. It's pretty fascinating that something so simple works, but you
can only listen from the position where the recording was taken.

I guess if you record using one of those complicated mic arrays, it may be
possible to simulate the effect of your pinnae in software, allowing you to
move around in a virtual environment, and hear the 3D audio from different
points?

[1]:
[https://en.m.wikipedia.org/wiki/Dummy_head_recording](https://en.m.wikipedia.org/wiki/Dummy_head_recording)

~~~
byproxy
Pink Floyd's (or, perhaps more correctly "Roger Waters'") "The Final Cut" made
extensive use of the binaural recording technique (or, perhaps, more correctly
"holophonics").

~~~
classichasclass
The best example on that album was the missile going through the "air" towards
impact. A good demo of the technology.

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modeless
Ambisonic recording is cool, but audio technology in general is full of
technobabble and pseudoscience, so I wonder how theoretically grounded these
systems are.

Are these companies actually understanding the science and producing well-
calibrated systems that can accurately record and reproduce pressure waves in
3D? Or are they just taking a bunch of microphones and gluing them in an
aesthetically interesting arrangement, and then playing them back in an ad-hoc
way?

~~~
beat
It's more engineering than science (especially considering the manifold
shortcomings of mic capsules and preamplification electronics), but yes, it's
real. I heard early analog systems over 25 years ago, and they were shocking.
They were also a bazillion dollars then, with a dedicated box to
discombobulate all the phase stuff. The sort of thing that's really easy to do
digitally now...

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philrw
Back in grad school our professor [Tom
Holman]([https://en.wikipedia.org/wiki/Tomlinson_Holman](https://en.wikipedia.org/wiki/Tomlinson_Holman))
did some amazing work in spatial sound, specifically for cinema. He chose to
double the number of channels from 5.1 to 10.2 and the results were pretty
amazing.

If my memory is working correctly, the channels chosen were Left, Left-Center,
Center, Right-Center, Right, High-Left, High-Right, Left Surround, Right
Surround, Back surround, and two low frequency channels. His research
indicated that the human ear has better vertical localization towards the
front (potentially having evolved to detect tree-dwelling predators, for
example), and experiments with dummy head recording produced inadequate
results for theatrical reproduction.

Sadly it doesn't seem to have caught on (yet), probably due to the expense of
having to retrofit cinemas. Anyway, it was really cool to listen to. I imagine
the use of ambisonic recording rigs will greatly benefit the 360° video
playback experience. Don't know what the other use cases might be yet.

~~~
blevin
Rather than adding fixed channels, many cinemas moved to Dolby Atmos, which
has 128 audio streams with spatial placement metadata. Those are rendered to
whatever speaker array is available.

[https://www.dolby.com/us/en/technologies/cinema/dolby-
atmos....](https://www.dolby.com/us/en/technologies/cinema/dolby-atmos.html)

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cuboidGoat
I have been trying to get professional musicians interested in ambisonics for
about 20 years, since I first learnt about it from my brother and I haven't
yet found a single one who is at all interested in experimenting with it.

I have had a few going as far as denying that ambisonics could even have any
kind of useful application in music at all.

The visual arts crowd seem far less dismissive, weirdly.

~~~
colanderman
This doesn't surprise me. I think most music – recorded sound – generally
falls into one of two categories: either:

• it's actually about the _music_ , not any particular "auditory experience",
so technologies like ambisonics – or heck, even stereo for that matter – are
perceived as gimmicky (akin to 3D TV), or

• it's about crafting a very _particular_ auditory experience: audio is mixed
in the studio so it matches exactly the artist's vision when played back to
your two eardrums.

Especially the latter case I think is _not_ served by ambisonics, because now
the artist has no control over how the product is consumed. I can only imagine
the difficulty involved in preparing a musical recording that sounds like
quality art when the listener can – and is expected to – completely change the
dynamics merely by tilting their neck. Sure you can deliver the "concert
experience" but no-one goes to a concert for the ability to hear the music
with their head cocked at a weird angle… so technologies like 3DIO I think
already serve this purpose well.

The analogy I would put forth is a movie where the viewer can control the
camera angle. (If I recall, this is actually a technology that exists to some
degree, and has found application pretty much only in pornography.) Good
cinematography carefully controls the viewer's attention and focus through use
of set design, camera angles and focus. Once you let the viewer just look
_anywhere_ , set design becomes immensely more complicated, and the artist
loses the creative control afforded by camera positioning.

Whereas, visual arts is _exactly_ where I would expect ambisonics to find
application. Visual arts is all about setting up exploratory experiences,
which is impossible with traditional stereo audio recording and fixed video
recording. With AR and ambisonics, now the art can exist digitally. I think
ambisonics will find application in video game design too, for the same
reason: now 3D soundscapes can be recorded, rather than simply synthesized.

Of course there are crossovers… I would be surprised if the ambient music
crowd (think Music for Airports) does not take to ambisonics. I'm curious
whether your experience differed between musical genres?

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dharma1
They are not hard to diy, 4 electret capsules like Primo EM184. But by the
time you've built the holder and preamps, might as well spend $300 on the Zoom
H3-VR.

I don't think they have much use outside VR - you basically need head tracking
for headphone use (or a lot of speakers)

~~~
codetrotter
How different is the H3-VR from the spatial audio of the Zoom H2n?

I’ve got an H2n though mostly I’ve only been using it with line-in to record
from my synth now and then, so I haven’t really used the spatial audio
feature... so actually come to think of it I’m not quite sure why I am even
asking :p Oh yeah, when I originally bought my H2n I did so because I wanted
to get into field recording.

In the end I didn’t find many interesting things to record; traffic - boring,
wind in the leaves in the forest - boring, birds singing - birds don’t sing
much here, trains - marginally entertaining the first time I recorded a train
coming to a stop.

I guess what I should be asking is: What sorts of sounds are you using the
H3-VR to capture? And do you find any advantage in using the H3-VR instead of
an H2n for said recordings?

~~~
dharma1
unless you're specifically recording ambisonic audio to go with 360 videos or
VR content I think you're fine with the H2n. The main difference with H3-VR is
the 6-degree gyro for aligning the soundfield correctly with the 360 video,
and onboard processing for previewing ambisonic sound with headphones

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umairadil
I’m just starting to learn the process of capturing and mixing 360 sound. I’m
confused though, is the “only” benefit of buying an ambisonic mic just have to
do with the ease of workflow? Sort of how it’s best to use a matched stereo
pair for stereo recordings if you want the best result with the least hassle?

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yoyobo
What do you all think of Creative Technology's "Super X-Fi"?

[http://www.mobilitytechzone.com/lte/news/2018/09/05/8812379....](http://www.mobilitytechzone.com/lte/news/2018/09/05/8812379.htm)

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yoyobo
[https://www.youtube.com/watch?v=mAidEm9_JYM](https://www.youtube.com/watch?v=mAidEm9_JYM)

~~~
dharma1
I think that could be really interesting. Ears/brain are very good at
localising sound, but normal headphones don't really work well for this.

Ossic raised $2.7m on Kickstarter to do something similar but failed to
deliver, I'm hoping Creative have better engineering and deeper pockets.

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mysterypie
I'm wondering if someone can clear up a related question. I've always heard
that two ears are needed to identify the direction of sound. However, I can
tell the direction of a sound when one ear is covered up and without moving my
head. Try it yourself: put a TV or other sound source behind yourself,
positioned a little to the left or right, cover one ear, and you'll see that
you can reliably tell whether it's more left or more right. So I think that
something more complicated is going on within the ear and that a single ear is
not strictly unidirectional.

~~~
boxcardavin
Localizing the sound isn't just a matter of hearing a phase shift between your
ears, you also have some 'knowledge' about how sound moves in a room, how your
ears change the sound, and what frequencies will be more prominent given which
side of you the sound is made on. The human brain kills it at real time signal
processing.

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mediaman
I read somewhere that the human (and ape) ear has evolved its unique set of
grooves and folds to help create sound reflections that allow the brain to
better spatially locate sound, even without phase shifting between both ears.

This also allows us to locate sound not only spatially along the axis between
the ears, but above and below as well.

I wonder if people using hearing aides, where the sound is recreated further
inside the ear, are less able to locate sound sources.

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hdhacker
If you like to see a full talk about this topic, held by a renowned German
microphone company "Schoeps Mikrofone", watch this video:
[https://youtu.be/K-ktLM0dQeA](https://youtu.be/K-ktLM0dQeA)

This high-end manufacturer might have a divergent perspective on those topics
in comparison to some other companies. Still, they supply recent high budget
productions in 3d audio, film or 3d audio sports events.

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Kiro
Will this be a big thing in ASMR?

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shkkmo
Something I don't often hear mentioned is auditory surveillance. An array of
highly sensitive 3D microphones with sophisticated processing seems like it
could completely destroy most remaining privacy that we have.

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peter_d_sherman
My intuition says that this idea, miniaturized to the size of an atom, might
bring back some heretofore unknown information about the atomic realm. Like an
atomic, multi-directional sound (or any wave in the EM spectrum) transducer,
and then bring that data to higher levels... Yes, I know I'm crazy... <g>

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peatfreak
I wonder whether these types of microphones are suitable for field recording.

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dgzl
Why not? The world is your stage, now in 3D.

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legionof7
It would be really cool to have music composed for 3D recording.

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tahw
This is not mathematically necessary at all. This just reads like astroturfing
for an overpriced mic retailer.

