Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fernando Lopez-Lezcano]

On 05/07/2018 07:05 PM, Fernando Lopez-Lezcano wrote:
...

So I bought a robotic arm. Len (from Core Sound) asked off-list about
it, so I'm including some information here. I got the WidowXL from
Trossen Robotics. Anything better (as far as I could find, not an
expert!) would have driven the price up ...


Just a quick update (maybe will help someone else). Most of this I knew 
beforehand...


The robotic arm is a bit on the short side to manipulate my microphones 
so as to get measurements at high elevations with respect to the 
horizontal plane (ie: can't tilt it enough without changing the location 
of the center of the array - or, with a different initial pose I can get 
high elevations for one of the hemispheres but not for the other). 
Shorter microphones should not have this problem. And the wrist servo 
has only 300 degrees of rotation which makes it not so useful to rotate 
the microphone for measurements.


So I modified it. I removed the gripper as I do not need it (which 
shortened the wrist which means I can get better elevation coverage) and 
replaced the wrist rotation servo with another one that has 360 degrees 
of rotation (so I can use it to rotate the microphone for measurements - 
this required me to design and 3d print a connection block). And 
modified the software that controls the arm to take these changes into 
account.


Looks more promising now...

Having played with it for a bit I know now it would not be out of the 
question to design a more suitable arm with the same type of servos and 
control board, it is a very flexible system. I could even lengthen the 
arm segments of the one I have, but enough modding for now... :-)


-- Fernando

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Peter P.]

Fernando,

I am sure you aware of the VariSphear robotic arm mic array that
Benjamin Bernschütz and collaborators built in 2010. I haven't found a
pic of it, but there are some articles (some in German only). Benjamin
might be on this list.

http://audiogroup.web.th-koeln.de/PUBLIKATIONEN/Bernschuetz_DAGA2010.pdf

https://s3.amazonaws.com/academia.edu.documents/40394369/SOFiA_-_Sound_Field_Analysis_Toolbox20151126-32622-k6bcza.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1525945973&Signature=qD%2FqTavFqjtvh91kf3hFwJXNkwk%3D&response-content-disposition=inline%3B%20filename%3DSOFiA_sound_field_analysis_toolbox.pdf


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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fernando Lopez-Lezcano]

On 05/08/2018 01:11 PM, Fons Adriaensen wrote:

On Mon, May 07, 2018 at 07:05:37PM -0700, Fernando Lopez-Lezcano wrote:


So I bought a robotic arm. Len (from Core Sound) asked off-list about it, so
I'm including some information here. I got the WidowXL from Trossen
Robotics. Anything better (as far as I could find, not an expert!) would
have driven the price up exponentially - this one is not cheap anyway. I
just spent two full days assembling it (lots of pieces, lots of screws).
Beware, ask before you buy as to delivery times - mine was delayed several
times and they were not very upfront about it (or just did not know).


One problem you may observe with robotic arms is vibration.


Yes, I did observe that "feature" :-)


It depends
on if the robot has mechanical brakes, or is using the actuator servos
to maintain a static position.


No brakes, just servos (it is a relatively "low cost" arm[*], or an 
expensive "toy", depending on how you look at it).



In the latter case there may be some
vibration due to marginally stable control loops. This is usually very
low level but a microphone will be all too happy to pick it up.

I wonder how the WidowXL performs regarding this.


Yes, it does make, sometimes, a tiny quite low level buzzing sound (no 
other way to describe it). I would like to imagine that it would not 
affect too much the recording of long sine sweeps at relatively high SPL 
levels... plus the mic mount attaches with a bit of padding. We'll see 
(hear?). See picture of one of my old prototypes taped to the grip (to 
test that the arm could actually handle the weight, had the needed 
torque, and could contort as needed :-) Not much testing done, just 
first impressions.


(busy designing and 3d printing the custom grips and mounts I need for 
the mics...)

-- Fernando

[*] at least for what I found online the next step up was about > $5-6k, 
for a good one but not industrial you could expect to pay >$20k , and 
for the real (industrial) thing maybe about the same but then you have 
to spend  in the environment in which you can run it safely... There 
were actually quite a few open source 3d printed arms but I could not 
find out that was convincing and already available.

-- next part --
A non-text attachment was scrubbed...
Name: octathingy_on_arm.jpg
Type: image/jpeg
Size: 463535 bytes
Desc: not available
URL: 

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fons Adriaensen]

On Mon, May 07, 2018 at 07:05:37PM -0700, Fernando Lopez-Lezcano wrote:

> So I bought a robotic arm. Len (from Core Sound) asked off-list about it, so
> I'm including some information here. I got the WidowXL from Trossen
> Robotics. Anything better (as far as I could find, not an expert!) would
> have driven the price up exponentially - this one is not cheap anyway. I
> just spent two full days assembling it (lots of pieces, lots of screws).
> Beware, ask before you buy as to delivery times - mine was delayed several
> times and they were not very upfront about it (or just did not know).

One problem you may observe with robotic arms is vibration. It depends
on if the robot has mechanical brakes, or is using the actuator servos
to maintain a static position. In the latter case there may be some
vibration due to marginally stable control loops. This is usually very
low level but a microphone will be all too happy to pick it up.

I wonder how the WidowXL performs regarding this. 

Ciao,

-- 
FA



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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Eric Benjamin]

For measurement purposes it should be possible to generate higher order 
responses using two or even one figure eight microphone. Place two figure eight 
microphones facing in the same direction spaced about one inch or so apart, 
depending on the frequency range desired. This could also be done by using a 
single figure eight microphone. Measure the impulse response in one direction, 
and then move the microphone about one inch away and measure another impulse 
response.  Subtract the two IRs and obtain a higher order IR. This is more 
difficult than my simple explanation. I haven’t done this, so caveat emptor.

Eric Benjamin.




From: Bo-Erik Sandholm
Sent: Tuesday, April 24, 2018 8:58 AM
To: sursound
Subject: Re: [Sursound] RIR measuring,how to capture a higher order Ambisonic 
room responce?

Thank you all, for your answers.
I received a lot of information.

I will start with FOA RIRs from my tetramic , it seems my ideas for
measuring higher orders are not realistic without a higher order microphone.

And FOA is probably good enough for my proof of concept.



Best Regards
Bo-Erik Sandholm
Stockholm

On Tue, 24 Apr 2018 03:59 umashankar manthravadi, 
wrote:

> I have been using a stepper motor (of the kind used in 3d printer ) driven
> by a low cost Arduino and motor control board. I 3d print a snug fitting
> fixture for the microphone with the motor shaft  aligned to the array
> centre. It is low cost so I design a fitting for each mic I test, including
> the Brahma-in-Zoom. A small Arduino script rotates the stepper 25 steps
> each time I press a button (for 16 positions) and 50 steps (for 8
> positions). I was worried about the stepper skipping with the weight of the
> microphone, but that is not happening, even with a five volt supply. I was
> ready with a thrust bearing between the motor housing and the microphone
> housing but it was not necessary. I plan to get rid of the switch and use a
> pulse on the right channel instead, though I generally do not like to
> automate things too much.
>
>
>
> umashankar
>
>
>
> Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
> 
> From: Sursound  on behalf of Fernando
> Lopez-Lezcano 
> Sent: Tuesday, April 24, 2018 1:40:56 AM
> To: Surround Sound discussion group
> Subject: Re: [Sursound] RIR measuring, how to capture a higher order
> Ambisonic room responce?
>
> On 04/23/2018 12:42 PM, Stefan Schreiber wrote:
> >> I can do the 4 measurements with 45 degrees rotation of my tetramic,
> that
> >> is not so difficult,  the next step to create a second order ambisonic
> >> RIR
> >>
> >> that is where I will fail :-).
>
> You would need to "calibrate" the created 8 capsule array. That is,
> record impulse responses all around it in a big space or anechoic room
> (enough to accurately sample the spherical harmonics you want), and then
> derive an A to B converter from that. I have some preliminary code in my
> SpHEAR project that tries to do that, but it is not a "push a button and
> you are done" thing at all...
>
> For Fons's code, and to do this the "right way"...
> On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> > ...  you'll have to sell your soul :-)
>
> :-P
>
> > I believe you might need a quite high precision to be successful even at
> > the first step...
> >
> > (A SF mike has narrowly spaced capsules, and needs calibrationThe
> > mechanical precision you need to measure 2nd order with a FOA mike is
> > IMHO high.)
>
> Based on my experience with the Octathingy's I have built I would agree,
> you would need to be very precise (and repeatable).
>
> In my case to get good calibration data I need to rotate the microphone
> with no wobble and at different orientations (or if it is not _exactly_
> perfect, try to get away with calibrating out the average delays to all
> capsules).
>
> BTW, I cannot move the speaker around which would probably be a better
> solution because of space constraints... I can barely get 4.5mSecs of IR
> data in the spaces I can use.
>
> > So the mathematical methods (based on FOA but improving the RIR
> > resolution, as suggested by Archontis) should be a better way to go
> > on... Especially since you could receive even higher resolutions/orders,
> > and in practice.
> >
> > So the presented ideas to capture 2nd order RIRs via a 1st order mike
> > are brilliant, but are they practical?
>
> Probably not practical IMHO.
>
> > And even if somebody could succeed in a very careful process: this does
> > not look to be a robust measurement method. ..
> >
> > We always talk about 

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fernando Lopez-Lezcano]

On 04/29/2018 06:13 AM, Dave Malham wrote:

Excellent - this is exactly the method I was about to suggest - steppers,
related hardware and motor control boards have been driven down in price so
much by the 3-d printing/cnc/maker revolution that it makes almost no sense
to do anything else.


Yes, I like that too... I was planning on adding a stepper and gear 
drive to my test rig (I turn it manually, not too hard).


This would have been fine for tetrahedral microphones and horizontal 
plane only measurements. The problem for me surfaced when I went to 
second order microphones and needed measurements above and below the 
horizontal plane. I built a "better" test rig that can tilt, added a 
small xy table to be able to "calibrate" the center of rotation (and of 
course 3d printed a fixture to attach the mic!), but I need to 
physically reposition the rig between each layer being measured. Not the 
best.


I was going for a different approach when it was suggested to me (both 
by my boss and a phd student here, thanks Chris & Elliot) that a robotic 
arm would be better and more general purpose. I was reluctant because of 
the cost...


(a bit off topic but maybe of interest anyway)

I was actually going to use a telescope mount (_not_ an equatorial mount 
which are the most common, apparently), I found one that would do what I 
needed, was not expensive, and I could control azimuth and elevation 
through rs232 (SkyWatcher AllView). I designed (on paper :-) a 
pantograph that would keep the microphone away from the mount, and 
replicate the movements. But again, lots of mechanical parts and tricky 
design. Better to spend time on the microphones.


So I bought a robotic arm. Len (from Core Sound) asked off-list about 
it, so I'm including some information here. I got the WidowXL from 
Trossen Robotics. Anything better (as far as I could find, not an 
expert!) would have driven the price up exponentially - this one is not 
cheap anyway. I just spent two full days assembling it (lots of pieces, 
lots of screws). Beware, ask before you buy as to delivery times - mine 
was delayed several times and they were not very upfront about it (or 
just did not know).


Anyway, I just did some preliminary tests today and it seems to be able 
to hold my microphone and move all the joints so as to point it in the 
right directions and rotate it accurately. Lots to do, but it is a start 
(to get better data).


-- Fernando



I would use the esp8266 arduino compatible wifi module
which costs about the same as a decent cappuccino - I paid about 4 euros
for one at the end of last year - which has a reasonably powerful 16 bit
processor and is quite capable of acting as a web server, so I'm doing that
and controlling my steppers from a web based interface on my mobile or
laptop. Note, however, that I've confined it to just my home network for
security sake - don't want people using it to influence the elections :-)

Dave
 PS Sorry once again I'm not currently doing this for audio - maybe one of
these days I'll get back to that.

On 24 April 2018 at 02:58, umashankar manthravadi 
wrote:


I have been using a stepper motor (of the kind used in 3d printer ) driven
by a low cost Arduino and motor control board. I 3d print a snug fitting
fixture for the microphone with the motor shaft  aligned to the array
centre. 


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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Marc Lavallée]

The ESP8266 can work as a wifi hotspot, so there's no need to connect it 
to a network. That's how many new gadgets are working, and that's what 
I'm doing now with a Raspberry Pi for a sound installation.  Instead of 
some Arduino board, I would use a Raspberry Pi to also record the sweeps 
(and even process them). What's missing the most is a well documented 
method to calibrate a microphone; but according to experts it's so 
difficult that even trying to think about it is a waste of time...


Marc


Le 2018-04-29 à 09:13 AM, Dave Malham a écrit :

Excellent - this is exactly the method I was about to suggest - steppers,
related hardware and motor control boards have been driven down in price so
much by the 3-d printing/cnc/maker revolution that it makes almost no sense
to do anything else. I would use the esp8266 arduino compatible wifi module
which costs about the same as a decent cappuccino - I paid about 4 euros
for one at the end of last year - which has a reasonably powerful 16 bit
processor and is quite capable of acting as a web server, so I'm doing that
and controlling my steppers from a web based interface on my mobile or
laptop. Note, however, that I've confined it to just my home network for
security sake - don't want people using it to influence the elections :-)

 Dave
  PS Sorry once again I'm not currently doing this for audio - maybe one of
these days I'll get back to that.

On 24 April 2018 at 02:58, umashankar manthravadi 
wrote:


I have been using a stepper motor (of the kind used in 3d printer ) driven
by a low cost Arduino and motor control board. I 3d print a snug fitting
fixture for the microphone with the motor shaft  aligned to the array
centre. It is low cost so I design a fitting for each mic I test, including
the Brahma-in-Zoom. A small Arduino script rotates the stepper 25 steps
each time I press a button (for 16 positions) and 50 steps (for 8
positions). I was worried about the stepper skipping with the weight of the
microphone, but that is not happening, even with a five volt supply. I was
ready with a thrust bearing between the motor housing and the microphone
housing but it was not necessary. I plan to get rid of the switch and use a
pulse on the right channel instead, though I generally do not like to
automate things too much.



umashankar



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10




From: Sursound  on behalf of Fernando
Lopez-Lezcano 
Sent: Tuesday, April 24, 2018 1:40:56 AM
To: Surround Sound discussion group
Subject: Re: [Sursound] RIR measuring, how to capture a higher order
Ambisonic room responce?

On 04/23/2018 12:42 PM, Stefan Schreiber wrote:

I can do the 4 measurements with 45 degrees rotation of my tetramic,

that

is not so difficult,  the next step to create a second order ambisonic
RIR

that is where I will fail :-).

You would need to "calibrate" the created 8 capsule array. That is,
record impulse responses all around it in a big space or anechoic room
(enough to accurately sample the spherical harmonics you want), and then
derive an A to B converter from that. I have some preliminary code in my
SpHEAR project that tries to do that, but it is not a "push a button and
you are done" thing at all...

For Fons's code, and to do this the "right way"...
On 03/27/2018 01:18 PM, Fons Adriaensen wrote:

...  you'll have to sell your soul :-)

:-P


I believe you might need a quite high precision to be successful even at
the first step...

(A SF mike has narrowly spaced capsules, and needs calibrationThe
mechanical precision you need to measure 2nd order with a FOA mike is
IMHO high.)

Based on my experience with the Octathingy's I have built I would agree,
you would need to be very precise (and repeatable).

In my case to get good calibration data I need to rotate the microphone
with no wobble and at different orientations (or if it is not _exactly_
perfect, try to get away with calibrating out the average delays to all
capsules).

BTW, I cannot move the speaker around which would probably be a better
solution because of space constraints... I can barely get 4.5mSecs of IR
data in the spaces I can use.


So the mathematical methods (based on FOA but improving the RIR
resolution, as suggested by Archontis) should be a better way to go
on... Especially since you could receive even higher resolutions/orders,
and in practice.

So the presented ideas to capture 2nd order RIRs via a 1st order mike
are brilliant, but are they practical?

Probably not practical IMHO.


And even if somebody could succeed in a very careful process: this does
not look to be a robust measurement method. ..

We always talk about the 1st reflections, in this case. Not reverb,
which is kind of statistical.

Of course you can try, but how much precision is really needed? (Should
be clarified before...)

I wo

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Dave Malham]

Excellent - this is exactly the method I was about to suggest - steppers,
related hardware and motor control boards have been driven down in price so
much by the 3-d printing/cnc/maker revolution that it makes almost no sense
to do anything else. I would use the esp8266 arduino compatible wifi module
which costs about the same as a decent cappuccino - I paid about 4 euros
for one at the end of last year - which has a reasonably powerful 16 bit
processor and is quite capable of acting as a web server, so I'm doing that
and controlling my steppers from a web based interface on my mobile or
laptop. Note, however, that I've confined it to just my home network for
security sake - don't want people using it to influence the elections :-)

Dave
 PS Sorry once again I'm not currently doing this for audio - maybe one of
these days I'll get back to that.

On 24 April 2018 at 02:58, umashankar manthravadi 
wrote:

> I have been using a stepper motor (of the kind used in 3d printer ) driven
> by a low cost Arduino and motor control board. I 3d print a snug fitting
> fixture for the microphone with the motor shaft  aligned to the array
> centre. It is low cost so I design a fitting for each mic I test, including
> the Brahma-in-Zoom. A small Arduino script rotates the stepper 25 steps
> each time I press a button (for 16 positions) and 50 steps (for 8
> positions). I was worried about the stepper skipping with the weight of the
> microphone, but that is not happening, even with a five volt supply. I was
> ready with a thrust bearing between the motor housing and the microphone
> housing but it was not necessary. I plan to get rid of the switch and use a
> pulse on the right channel instead, though I generally do not like to
> automate things too much.
>
>
>
> umashankar
>
>
>
> Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
> 
> From: Sursound  on behalf of Fernando
> Lopez-Lezcano 
> Sent: Tuesday, April 24, 2018 1:40:56 AM
> To: Surround Sound discussion group
> Subject: Re: [Sursound] RIR measuring, how to capture a higher order
> Ambisonic room responce?
>
> On 04/23/2018 12:42 PM, Stefan Schreiber wrote:
> >> I can do the 4 measurements with 45 degrees rotation of my tetramic,
> that
> >> is not so difficult,  the next step to create a second order ambisonic
> >> RIR
> >>
> >> that is where I will fail :-).
>
> You would need to "calibrate" the created 8 capsule array. That is,
> record impulse responses all around it in a big space or anechoic room
> (enough to accurately sample the spherical harmonics you want), and then
> derive an A to B converter from that. I have some preliminary code in my
> SpHEAR project that tries to do that, but it is not a "push a button and
> you are done" thing at all...
>
> For Fons's code, and to do this the "right way"...
> On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> > ...  you'll have to sell your soul :-)
>
> :-P
>
> > I believe you might need a quite high precision to be successful even at
> > the first step...
> >
> > (A SF mike has narrowly spaced capsules, and needs calibrationThe
> > mechanical precision you need to measure 2nd order with a FOA mike is
> > IMHO high.)
>
> Based on my experience with the Octathingy's I have built I would agree,
> you would need to be very precise (and repeatable).
>
> In my case to get good calibration data I need to rotate the microphone
> with no wobble and at different orientations (or if it is not _exactly_
> perfect, try to get away with calibrating out the average delays to all
> capsules).
>
> BTW, I cannot move the speaker around which would probably be a better
> solution because of space constraints... I can barely get 4.5mSecs of IR
> data in the spaces I can use.
>
> > So the mathematical methods (based on FOA but improving the RIR
> > resolution, as suggested by Archontis) should be a better way to go
> > on... Especially since you could receive even higher resolutions/orders,
> > and in practice.
> >
> > So the presented ideas to capture 2nd order RIRs via a 1st order mike
> > are brilliant, but are they practical?
>
> Probably not practical IMHO.
>
> > And even if somebody could succeed in a very careful process: this does
> > not look to be a robust measurement method. ..
> >
> > We always talk about the 1st reflections, in this case. Not reverb,
> > which is kind of statistical.
> >
> > Of course you can try, but how much precision is really needed? (Should
> > be clarified before...)
>
> I would hav

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Bo-Erik Sandholm]

Thank you all, for your answers.
I received a lot of information.

I will start with FOA RIRs from my tetramic , it seems my ideas for
measuring higher orders are not realistic without a higher order microphone.

And FOA is probably good enough for my proof of concept.



Best Regards
Bo-Erik Sandholm
Stockholm

On Tue, 24 Apr 2018 03:59 umashankar manthravadi, 
wrote:

> I have been using a stepper motor (of the kind used in 3d printer ) driven
> by a low cost Arduino and motor control board. I 3d print a snug fitting
> fixture for the microphone with the motor shaft  aligned to the array
> centre. It is low cost so I design a fitting for each mic I test, including
> the Brahma-in-Zoom. A small Arduino script rotates the stepper 25 steps
> each time I press a button (for 16 positions) and 50 steps (for 8
> positions). I was worried about the stepper skipping with the weight of the
> microphone, but that is not happening, even with a five volt supply. I was
> ready with a thrust bearing between the motor housing and the microphone
> housing but it was not necessary. I plan to get rid of the switch and use a
> pulse on the right channel instead, though I generally do not like to
> automate things too much.
>
>
>
> umashankar
>
>
>
> Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
> 
> From: Sursound  on behalf of Fernando
> Lopez-Lezcano 
> Sent: Tuesday, April 24, 2018 1:40:56 AM
> To: Surround Sound discussion group
> Subject: Re: [Sursound] RIR measuring, how to capture a higher order
> Ambisonic room responce?
>
> On 04/23/2018 12:42 PM, Stefan Schreiber wrote:
> >> I can do the 4 measurements with 45 degrees rotation of my tetramic,
> that
> >> is not so difficult,  the next step to create a second order ambisonic
> >> RIR
> >>
> >> that is where I will fail :-).
>
> You would need to "calibrate" the created 8 capsule array. That is,
> record impulse responses all around it in a big space or anechoic room
> (enough to accurately sample the spherical harmonics you want), and then
> derive an A to B converter from that. I have some preliminary code in my
> SpHEAR project that tries to do that, but it is not a "push a button and
> you are done" thing at all...
>
> For Fons's code, and to do this the "right way"...
> On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> > ...  you'll have to sell your soul :-)
>
> :-P
>
> > I believe you might need a quite high precision to be successful even at
> > the first step...
> >
> > (A SF mike has narrowly spaced capsules, and needs calibrationThe
> > mechanical precision you need to measure 2nd order with a FOA mike is
> > IMHO high.)
>
> Based on my experience with the Octathingy's I have built I would agree,
> you would need to be very precise (and repeatable).
>
> In my case to get good calibration data I need to rotate the microphone
> with no wobble and at different orientations (or if it is not _exactly_
> perfect, try to get away with calibrating out the average delays to all
> capsules).
>
> BTW, I cannot move the speaker around which would probably be a better
> solution because of space constraints... I can barely get 4.5mSecs of IR
> data in the spaces I can use.
>
> > So the mathematical methods (based on FOA but improving the RIR
> > resolution, as suggested by Archontis) should be a better way to go
> > on... Especially since you could receive even higher resolutions/orders,
> > and in practice.
> >
> > So the presented ideas to capture 2nd order RIRs via a 1st order mike
> > are brilliant, but are they practical?
>
> Probably not practical IMHO.
>
> > And even if somebody could succeed in a very careful process: this does
> > not look to be a robust measurement method. ..
> >
> > We always talk about the 1st reflections, in this case. Not reverb,
> > which is kind of statistical.
> >
> > Of course you can try, but how much precision is really needed? (Should
> > be clarified before...)
>
> I would have to go to my data to get some numbers... I definitely can
> see effects at high frequencies when the data capture is not precise
> (I'm in the process of trying to build a better measuring rig).
>
> -- Fernando
>
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[umashankar manthravadi]

I have been using a stepper motor (of the kind used in 3d printer ) driven by a 
low cost Arduino and motor control board. I 3d print a snug fitting fixture for 
the microphone with the motor shaft  aligned to the array centre. It is low 
cost so I design a fitting for each mic I test, including the Brahma-in-Zoom. A 
small Arduino script rotates the stepper 25 steps each time I press a button 
(for 16 positions) and 50 steps (for 8 positions). I was worried about the 
stepper skipping with the weight of the microphone, but that is not happening, 
even with a five volt supply. I was ready with a thrust bearing between the 
motor housing and the microphone housing but it was not necessary. I plan to 
get rid of the switch and use a pulse on the right channel instead, though I 
generally do not like to automate things too much.



umashankar



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10




From: Sursound  on behalf of Fernando 
Lopez-Lezcano 
Sent: Tuesday, April 24, 2018 1:40:56 AM
To: Surround Sound discussion group
Subject: Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic 
room responce?

On 04/23/2018 12:42 PM, Stefan Schreiber wrote:
>> I can do the 4 measurements with 45 degrees rotation of my tetramic, that
>> is not so difficult,  the next step to create a second order ambisonic
>> RIR
>>
>> that is where I will fail :-).

You would need to "calibrate" the created 8 capsule array. That is,
record impulse responses all around it in a big space or anechoic room
(enough to accurately sample the spherical harmonics you want), and then
derive an A to B converter from that. I have some preliminary code in my
SpHEAR project that tries to do that, but it is not a "push a button and
you are done" thing at all...

For Fons's code, and to do this the "right way"...
On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> ...  you'll have to sell your soul :-)

:-P

> I believe you might need a quite high precision to be successful even at
> the first step...
>
> (A SF mike has narrowly spaced capsules, and needs calibrationThe
> mechanical precision you need to measure 2nd order with a FOA mike is
> IMHO high.)

Based on my experience with the Octathingy's I have built I would agree,
you would need to be very precise (and repeatable).

In my case to get good calibration data I need to rotate the microphone
with no wobble and at different orientations (or if it is not _exactly_
perfect, try to get away with calibrating out the average delays to all
capsules).

BTW, I cannot move the speaker around which would probably be a better
solution because of space constraints... I can barely get 4.5mSecs of IR
data in the spaces I can use.

> So the mathematical methods (based on FOA but improving the RIR
> resolution, as suggested by Archontis) should be a better way to go
> on... Especially since you could receive even higher resolutions/orders,
> and in practice.
>
> So the presented ideas to capture 2nd order RIRs via a 1st order mike
> are brilliant, but are they practical?

Probably not practical IMHO.

> And even if somebody could succeed in a very careful process: this does
> not look to be a robust measurement method. ..
>
> We always talk about the 1st reflections, in this case. Not reverb,
> which is kind of statistical.
>
> Of course you can try, but how much precision is really needed? (Should
> be clarified before...)

I would have to go to my data to get some numbers... I definitely can
see effects at high frequencies when the data capture is not precise
(I'm in the process of trying to build a better measuring rig).

-- Fernando

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fernando Lopez-Lezcano]

On 04/23/2018 03:19 PM, Fons Adriaensen wrote:

On Mon, Apr 23, 2018 at 01:10:56PM -0700, Fernando Lopez-Lezcano wrote:

In my case to get good calibration data I need to rotate the microphone with
no wobble and at different orientations (or if it is not _exactly_ perfect,
try to get away with calibrating out the average delays to all capsules).


There's practically no way to obtain precise positioning,


Yes, I get (measurable) wobble even after "calibrating" the position of 
the array (I have a small XY table at the bottom of the rig to be able 
to offset the center of the array with respect to the center of 
rotation). No way to make this "perfect", just the stiffness of all 
parts and play is enough to create small errors.



unless you'd use a robot to rotate the microphone,


Funny you would say that, I have a robotic arm on order (I should have 
gotten it a couple of weeks ago but some part was apparently on 
back-order)...



and that comes with its own sort
of potential problems (like reflections on the robot arm).


Indeed, at this point I'm not sure it is going to be a solution, or just 
another problem :-) A robot arm that is big enough to be "out of the 
way" would be way too expensive. Very cheap ones are too small and don't 
have enough carrying capacity and precision. Some are obviously too 
"fat" and will be a pain in terms of reflections, or too short and not 
enough reach. We'll see if what I'm getting is good enough...


At least it should make the task of doing many repeatable measurements 
not so insane, at this point everything is manual (I am the robot).


Of course driving the robotic arm so that it positions the center of the 
microphone at the right spot is probably not going to be easy either. 
Again, physical interface, tolerances, play... Hmmm, jack-delay and arm, 
feedback loop, hmmm[*]...



The only practical solution is to make the processing software detect
small position (and other) errors and compensate for them.


I reached the same conclusion, and that is what I'm doing now. So far it 
looks like an improvement.


-- Fernando

[*] unstable system, the arm goes wild and destroys the microphone, 
nothing left to measure!, bliss.


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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fons Adriaensen]

On Mon, Apr 23, 2018 at 01:10:56PM -0700, Fernando Lopez-Lezcano wrote:
 
> You would need to "calibrate" the created 8 capsule array. That is, record
> impulse responses all around it in a big space or anechoic room (enough to
> accurately sample the spherical harmonics you want), and then derive an A to
> B converter from that. I have some preliminary code in my SpHEAR project
> that tries to do that, but it is not a "push a button and you are done"
> thing at all...

Indeed not. To start with, how to do measurements that can actually be
trusted is something you learn only with experience. Rest assured that
the first five times you do this will produce near useless results,
and you will notice that only *after* most of the processing is done.
That is assuming that you have sanity checks in the procedure at all.
If not, the result can easily look OK but actually be totally wrong.

> In my case to get good calibration data I need to rotate the microphone with
> no wobble and at different orientations (or if it is not _exactly_ perfect,
> try to get away with calibrating out the average delays to all capsules).

There's practically no way to obtain precise positioning, unless you'd 
use a robot to rotate the microphone, and that comes with its own sort
of potential problems (like reflections on the robot arm).
The only practical solution is to make the processing software detect
small position (and other) errors and compensate for them. This, plus
sanity checks, makes up at least three quarters of the code I use to
calibrate Tetra and Octomics. And those parts are also the most
difficult to get right and verified.

So unless you want to spend a few months full time to develop and test
all of this, I'd stronly advise to not even try it.

Returning to the original problem: it is perfectly possible to 
obtain higher order room IRs from first order measurements. 
The dominant early reflections tend to be separated in time, so
they can be isolated and recreated in higher order. For the 
reverb tail only the statistics need to be correct. It's
not a trivial thing, but it can and has been done. 

Ciao,

-- 
FA

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Stefan Schreiber]

Citando Eric Benjamin :

I did this rotation and calibration operation. Unfortunately the  
results were not great. When the array is rotated it has to overlay  
the previous position perfectly.  There is also a tendency for the  
mic stand to wobble when it rotates. These results are shown in my  
AES paper on the second order microphone.




 Eric Benjamin


As I suspected...

SF microphones are precision instruments! If even stand wobbling is an  
issue I would say:


Forget about combining 4 separate IR measurements, and either

- use the available mathematical methods for FOA RIRs to increase the  
resolution/order.


- use an Octomic (or alternatives) anyway. 

Thanks,

Stefan


From: Fernando Lopez-Lezcano

 Sent: Monday, April 23, 2018 1:11 PM

 To: Surround Sound discussion group

 Subject: Re: [Sursound] RIR measuring,how to capture a higher order  
Ambisonic room responce?




 On 04/23/2018 12:42 PM, Stefan Schreiber wrote:


I can do the 4 measurements with 45 degrees rotation of my tetramic, that

 is not so difficult,  the next step to create a second order ambisonic

 RIR



 that is where I will fail :-).


You would need to "calibrate" the created 8 capsule array. That is,

 record impulse responses all around it in a big space or anechoic room

 (enough to accurately sample the spherical harmonics you want), and then

 derive an A to B converter from that. I have some preliminary code in my

 SpHEAR project that tries to do that, but it is not a "push a button and

 you are done" thing at all...

 ___

 Sursound mailing list

  
surso...@music.vt.eduhttps://mail.music.vt.edu/mailman/listinfo/sursound[1]  
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Eric Benjamin]

I did this rotation and calibration operation. Unfortunately the results were 
not great. When the array is rotated it has to overlay the previous position 
perfectly.  There is also a tendency for the mic stand to wobble when it 
rotates. These results are shown in my AES paper on the second order microphone.

Eric Benjamin

From: Fernando Lopez-Lezcano
Sent: Monday, April 23, 2018 1:11 PM
To: Surround Sound discussion group
Subject: Re: [Sursound] RIR measuring,how to capture a higher order Ambisonic 
room responce?

On 04/23/2018 12:42 PM, Stefan Schreiber wrote:
>> I can do the 4 measurements with 45 degrees rotation of my tetramic, that
>> is not so difficult,  the next step to create a second order ambisonic
>> RIR
>>
>> that is where I will fail :-).

You would need to "calibrate" the created 8 capsule array. That is, 
record impulse responses all around it in a big space or anechoic room 
(enough to accurately sample the spherical harmonics you want), and then 
derive an A to B converter from that. I have some preliminary code in my 
SpHEAR project that tries to do that, but it is not a "push a button and 
you are done" thing at all...

For Fons's code, and to do this the "right way"...
On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> ...  you'll have to sell your soul :-)

:-P

> I believe you might need a quite high precision to be successful even at
> the first step...
>
> (A SF mike has narrowly spaced capsules, and needs calibrationThe
> mechanical precision you need to measure 2nd order with a FOA mike is
> IMHO high.)

Based on my experience with the Octathingy's I have built I would agree, 
you would need to be very precise (and repeatable).

In my case to get good calibration data I need to rotate the microphone 
with no wobble and at different orientations (or if it is not _exactly_ 
perfect, try to get away with calibrating out the average delays to all 
capsules).

BTW, I cannot move the speaker around which would probably be a better 
solution because of space constraints... I can barely get 4.5mSecs of IR 
data in the spaces I can use.

> So the mathematical methods (based on FOA but improving the RIR
> resolution, as suggested by Archontis) should be a better way to go
> on... Especially since you could receive even higher resolutions/orders,
> and in practice.
>
> So the presented ideas to capture 2nd order RIRs via a 1st order mike
> are brilliant, but are they practical?

Probably not practical IMHO.

> And even if somebody could succeed in a very careful process: this does
> not look to be a robust measurement method. ..
>
> We always talk about the 1st reflections, in this case. Not reverb,
> which is kind of statistical.
>
> Of course you can try, but how much precision is really needed? (Should
> be clarified before...)

I would have to go to my data to get some numbers... I definitely can 
see effects at high frequencies when the data capture is not precise 
(I'm in the process of trying to build a better measuring rig).

-- Fernando

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fernando Lopez-Lezcano]

On 04/23/2018 12:42 PM, Stefan Schreiber wrote:

I can do the 4 measurements with 45 degrees rotation of my tetramic, that
is not so difficult,  the next step to create a second order ambisonic
RIR

that is where I will fail :-).


You would need to "calibrate" the created 8 capsule array. That is, 
record impulse responses all around it in a big space or anechoic room 
(enough to accurately sample the spherical harmonics you want), and then 
derive an A to B converter from that. I have some preliminary code in my 
SpHEAR project that tries to do that, but it is not a "push a button and 
you are done" thing at all...


For Fons's code, and to do this the "right way"...
On 03/27/2018 01:18 PM, Fons Adriaensen wrote:

...  you'll have to sell your soul :-)


:-P


I believe you might need a quite high precision to be successful even at
the first step...

(A SF mike has narrowly spaced capsules, and needs calibrationThe
mechanical precision you need to measure 2nd order with a FOA mike is
IMHO high.)


Based on my experience with the Octathingy's I have built I would agree, 
you would need to be very precise (and repeatable).


In my case to get good calibration data I need to rotate the microphone 
with no wobble and at different orientations (or if it is not _exactly_ 
perfect, try to get away with calibrating out the average delays to all 
capsules).


BTW, I cannot move the speaker around which would probably be a better 
solution because of space constraints... I can barely get 4.5mSecs of IR 
data in the spaces I can use.



So the mathematical methods (based on FOA but improving the RIR
resolution, as suggested by Archontis) should be a better way to go
on... Especially since you could receive even higher resolutions/orders,
and in practice.

So the presented ideas to capture 2nd order RIRs via a 1st order mike
are brilliant, but are they practical?


Probably not practical IMHO.


And even if somebody could succeed in a very careful process: this does
not look to be a robust measurement method. ..

We always talk about the 1st reflections, in this case. Not reverb,
which is kind of statistical.

Of course you can try, but how much precision is really needed? (Should
be clarified before...)


I would have to go to my data to get some numbers... I definitely can 
see effects at high frequencies when the data capture is not precise 
(I'm in the process of trying to build a better measuring rig).


-- Fernando

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Stefan Schreiber]

I can do the 4 measurements with 45 degrees rotation of my tetramic, that

is not so difficult,  the next step to create a second order ambisonic RIR

that is where I will fail :-).


I believe you might need a quite high precision to be successful even  
at the first step...


(A SF mike has narrowly spaced capsules, and needs calibrationThe  
mechanical precision you need to measure 2nd order with a FOA mike is  
IMHO high.)


So the mathematical methods (based on FOA but improving the RIR  
resolution, as suggested by Archontis) should be a better way to go  
on... Especially since you could receive even higher  
resolutions/orders, and in practice.


So the presented ideas to capture 2nd order RIRs via a 1st order mike  
are brilliant, but are they practical?


And even if somebody could succeed in a very careful process: this  
does not look to be a robust measurement method. ..


We always talk about the 1st reflections, in this case. Not reverb,  
which is kind of statistical.


Of course you can try, but how much precision is rally needed? (Should  
be clarified before...)


Stefan

——

Citando Bo-Erik Sandholm :


I can do the 4 measurements with 45 degrees rotation of my tetramic, that

 is not so difficult,  the next step to create a second order ambisonic RIR

 that is where I will fail :-).



 I will need a more detailed step by step instruction to reach my goal :-).



 Bo-Erik

 Stockholm



 On Mon, 23 Apr 2018 21:02 jack reynolds,  wrote:


you are right fons.



 it is an octohedron with the top four rotated 45 degrees.



 but i would have thought two tetramic IRs at 90 rotated 90 degress from

 each other would give you quite good coverage.



 rotated 45, 90 and 135 would be even better! Plus another couple for up and

 down?



 J







 On 23 April 2018 at 19:50, Fons Adriaensen  wrote:



 On Mon, Apr 23, 2018 at 07:18:33PM +0100, jack reynolds wrote:



 > indeed. apologies, it is 90 degrees.



 Again no. To cover all the directions of the Octomic capsules

 with a Tetramic you need 4 orientations of the Tetramic (and

 you get another 8 directions as a bonus).



 Ciao,



 --

 FA





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 --



 07889727365



 02036861372



 3 Swimmers Lane

 Haggerston

 London

 E2 8FR





 www.facebook.com/reynoldsmicrophones[1]



 www.sohovr.co.uk[2]

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Stefan Schreiber]

But Bo-Erik already wrote this...

So do we agree on 4 orientations? (Unless you just buy an Octomic, of  
course...)


Best,

Stefan

———-

Citando Fons Adriaensen :


On Mon, Apr 23, 2018 at 07:18:33PM +0100, jack reynolds wrote:


indeed. apologies, it is 90 degrees.


Again no. To cover all the directions of the Octomic capsules

 with a Tetramic you need 4 orientations of the Tetramic (and

 you get another 8 directions as a bonus).



 Ciao,



 --

 FA





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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Bo-Erik Sandholm]

I can do the 4 measurements with 45 degrees rotation of my tetramic, that
is not so difficult,  the next step to create a second order ambisonic RIR
that is where I will fail :-).

I will need a more detailed step by step instruction to reach my goal :-).

Bo-Erik
Stockholm

On Mon, 23 Apr 2018 21:02 jack reynolds,  wrote:

> you are right fons.
>
> it is an octohedron with the top four rotated 45 degrees.
>
> but i would have thought two tetramic IRs at 90 rotated 90 degress from
> each other would give you quite good coverage.
>
> rotated 45, 90 and 135 would be even better! Plus another couple for up and
> down?
>
> J
>
>
>
> On 23 April 2018 at 19:50, Fons Adriaensen  wrote:
>
> > On Mon, Apr 23, 2018 at 07:18:33PM +0100, jack reynolds wrote:
> >
> > > indeed. apologies, it is 90 degrees.
> >
> > Again no. To cover all the directions of the Octomic capsules
> > with a Tetramic you need 4 orientations of the Tetramic (and
> > you get another 8 directions as a bonus).
> >
> > Ciao,
> >
> > --
> > FA
> >
> >
> > ___
> > 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.
> >
>
>
>
> --
>
> 07889727365
>
> 02036861372
>
> 3 Swimmers Lane
> Haggerston
> London
> E2 8FR
>
>
> www.facebook.com/reynoldsmicrophones
>
> www.sohovr.co.uk
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[jack reynolds]

you are right fons.

it is an octohedron with the top four rotated 45 degrees.

but i would have thought two tetramic IRs at 90 rotated 90 degress from
each other would give you quite good coverage.

rotated 45, 90 and 135 would be even better! Plus another couple for up and
down?

J



On 23 April 2018 at 19:50, Fons Adriaensen  wrote:

> On Mon, Apr 23, 2018 at 07:18:33PM +0100, jack reynolds wrote:
>
> > indeed. apologies, it is 90 degrees.
>
> Again no. To cover all the directions of the Octomic capsules
> with a Tetramic you need 4 orientations of the Tetramic (and
> you get another 8 directions as a bonus).
>
> Ciao,
>
> --
> FA
>
>
> ___
> 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.
>



-- 

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fons Adriaensen]

On Mon, Apr 23, 2018 at 07:18:33PM +0100, jack reynolds wrote:

> indeed. apologies, it is 90 degrees.

Again no. To cover all the directions of the Octomic capsules
with a Tetramic you need 4 orientations of the Tetramic (and
you get another 8 directions as a bonus).

Ciao,

-- 
FA


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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fons Adriaensen]

On Mon, Apr 23, 2018 at 12:24:47PM +0100, jack reynolds wrote:

> The new coresound octomic is based on two tetramics, with one rotated 45
> degrees from the other

This is simply not true.

Ciao,

-- 
FA


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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[jack reynolds]

indeed. apologies, it is 90 degrees.

On 23 April 2018 at 18:31, Bo-Erik Sandholm  wrote:

> As I see it to capture the signals for the upper layers of octomic with a
> tetra mic you rotate the mic 90 degrees between the takes..
> To capture the lower octomic  elements layer go back to initial position,
> then rotate Tetra mic 45 degrees and then 90 degrees for 2  recordings.
>
> So 4 rotation direction to place the tetra mic elements in same positions
> as the 8 Octomic capsules.
>
> select the 8 A signals that corresponds to the octomic positions...
>
> Then get our hands on the octomic software if possible and hopefully
> translate the tetramic calibration file in to a octomic calibration file,
> might be possible.
>
> This has only a chance to work for IR measurements and if the rotation of
> the tetramic is done without moving the center point of the mic head.
>
> I hope this is possible, it should be a great new use of a tetramic to be
> able with a little work to create second order room Impulse responses.
>
>  Bo-Erik
>
> 2018-04-23 19:10 GMT+02:00 Fernando Lopez-Lezcano <
> na...@ccrma.stanford.edu>
> :
>
> > On 04/23/2018 04:24 AM, jack reynolds wrote:
> >
> >> The new coresound octomic is based on two tetramics, with one rotated 45
> >> degrees from the other,
> >>
> >
> > Hmm, does not look like that to me. If you, for example, take any two
> > opposite capsules in the upper ring as part of one tetrahedral
> microphone,
> > there are no capsules in the lower ring that would match the lower half
> of
> > that microphone (they are rotated 45 degrees from where they should be).
> >
> > -- Fernando
> >
> >
> > so if you could work out how the second order
> >> B-format is extracted from the octomic array, you could potentially take
> >> an
> >> A-format reponse with your tetramic, rotate the mic 45 degrees and
> capture
> >> another, then process all eight channels?
> >> Just a thought.
> >>
> >> Jack
> >>
> >> On 23 April 2018 at 11:51, Bo-Erik Sandholm 
> wrote:
> >>
> >> Have never used Max, I need just 2, but probably 4 sound source
> positions
> >>> and one listening position.
> >>> But the listening position should have full spherical  ambisonic
> >>> soundfield.
> >>> But the result should be ambisonic IR's for these 4 sources.
> >>>
> >>> The question is could upsampling be used ?
> >>>
> >>> BR Bo-Erik
> >>>
> >>>
> >>>
> >>> 2018-04-23 10:47 GMT+02:00 Hyunkook Lee :
> >>>
> >>> Indeed HIRT is the best IR capture package for Max.  There is also
> HAART,
> >>>> which is a standalone Max application we developed using HIRT. This
> >>>> software is all in one box for multichannel IR capture (24 mics x 24
> >>>> sources), acoustic parameter analysis and binauralisation. The
> analysis
> >>>> part is still under development, but the IR capture and
> binauralisation
> >>>> parts are fully working. You can download it here
> >>>>
> >>>> http://eprints.hud.ac.uk/id/eprint/24579/
> >>>>
> >>>> Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel
> >>>>
> >>> mic
> >>>
> >>>> array configurations from stereo to 9ch 3D using HAART. The library
> >>>> comes
> >>>> with a Max renderer where you can convolve dry sources or signals fed
> >>>>
> >>> from
> >>>
> >>>> DAW with the mic array IRs for simultaneous comparisons between
> >>>>
> >>> techniques.
> >>>
> >>>>
> >>>> https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer
> >>>>
> >>>> Best,
> >>>> Hyunkook
> >>>> =
> >>>> Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
> >>>> Senior Lecturer in Music Technology
> >>>> Leader of the Applied Psychoacoustics Laboratory (APL)
> >>>> http://www.hud.ac.uk/apl
> >>>> http://www.hyunkooklee.com
> >>>> Phone: +44 (0)1484 471893
> >>>> Email: h@hud.ac.uk
> >>>> Office: CE 2 /14a
> >>>> School of Computing and Engineering
> >>>> University of Huddersfield
> >>>> Huddersfield
> >>>> HD1 3DH
&

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Stefan Schreiber]

Stunning discussion here!

Now this is why it makes sense to keep your sursound membership...  😎

BR

Stefan

Citando Politis Archontis :

By the way one could actually use only one microphone, measure the  
RIR, rotate it to another point, repeat the measurement, and make a  
virtual array of hundreds or thousands of points for high-order RIR  
recording. This has actually been done and the work published by  
Boaz Rafaely and his research group.




 Regards,

 Archontis Politis


On 23 Apr 2018, at 20:31, Bo-Erik Sandholm  wrote:



 As I see it to capture the signals for the upper layers of octomic with a

 tetra mic you rotate the mic 90 degrees between the takes..

 To capture the lower octomic  elements layer go back to initial position,

 then rotate Tetra mic 45 degrees and then 90 degrees for 2  recordings.



 So 4 rotation direction to place the tetra mic elements in same positions

 as the 8 Octomic capsules.



 select the 8 A signals that corresponds to the octomic positions...



 Then get our hands on the octomic software if possible and hopefully

 translate the tetramic calibration file in to a octomic calibration file,

 might be possible.



 This has only a chance to work for IR measurements and if the rotation of

 the tetramic is done without moving the center point of the mic head.



 I hope this is possible, it should be a great new use of a tetramic to be

 able with a little work to create second order room Impulse responses.



 Bo-Erik



 2018-04-23 19:10 GMT+02:00 Fernando Lopez-Lezcano  



 :


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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Politis Archontis]

By the way one could actually use only one microphone, measure the RIR, rotate 
it to another point, repeat the measurement, and make a virtual array of 
hundreds or thousands of points for high-order RIR recording. This has actually 
been done and the work published by Boaz Rafaely and his research group.

Regards,
Archontis Politis



> On 23 Apr 2018, at 20:31, Bo-Erik Sandholm  wrote:
> 
> As I see it to capture the signals for the upper layers of octomic with a
> tetra mic you rotate the mic 90 degrees between the takes..
> To capture the lower octomic  elements layer go back to initial position,
> then rotate Tetra mic 45 degrees and then 90 degrees for 2  recordings.
> 
> So 4 rotation direction to place the tetra mic elements in same positions
> as the 8 Octomic capsules.
> 
> select the 8 A signals that corresponds to the octomic positions...
> 
> Then get our hands on the octomic software if possible and hopefully
> translate the tetramic calibration file in to a octomic calibration file,
> might be possible.
> 
> This has only a chance to work for IR measurements and if the rotation of
> the tetramic is done without moving the center point of the mic head.
> 
> I hope this is possible, it should be a great new use of a tetramic to be
> able with a little work to create second order room Impulse responses.
> 
> Bo-Erik
> 
> 2018-04-23 19:10 GMT+02:00 Fernando Lopez-Lezcano 
> :
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Bo-Erik Sandholm]

As I see it to capture the signals for the upper layers of octomic with a
tetra mic you rotate the mic 90 degrees between the takes..
To capture the lower octomic  elements layer go back to initial position,
then rotate Tetra mic 45 degrees and then 90 degrees for 2  recordings.

So 4 rotation direction to place the tetra mic elements in same positions
as the 8 Octomic capsules.

select the 8 A signals that corresponds to the octomic positions...

Then get our hands on the octomic software if possible and hopefully
translate the tetramic calibration file in to a octomic calibration file,
might be possible.

This has only a chance to work for IR measurements and if the rotation of
the tetramic is done without moving the center point of the mic head.

I hope this is possible, it should be a great new use of a tetramic to be
able with a little work to create second order room Impulse responses.

 Bo-Erik

2018-04-23 19:10 GMT+02:00 Fernando Lopez-Lezcano 
:

> On 04/23/2018 04:24 AM, jack reynolds wrote:
>
>> The new coresound octomic is based on two tetramics, with one rotated 45
>> degrees from the other,
>>
>
> Hmm, does not look like that to me. If you, for example, take any two
> opposite capsules in the upper ring as part of one tetrahedral microphone,
> there are no capsules in the lower ring that would match the lower half of
> that microphone (they are rotated 45 degrees from where they should be).
>
> -- Fernando
>
>
> so if you could work out how the second order
>> B-format is extracted from the octomic array, you could potentially take
>> an
>> A-format reponse with your tetramic, rotate the mic 45 degrees and capture
>> another, then process all eight channels?
>> Just a thought.
>>
>> Jack
>>
>> On 23 April 2018 at 11:51, Bo-Erik Sandholm  wrote:
>>
>> Have never used Max, I need just 2, but probably 4 sound source positions
>>> and one listening position.
>>> But the listening position should have full spherical  ambisonic
>>> soundfield.
>>> But the result should be ambisonic IR's for these 4 sources.
>>>
>>> The question is could upsampling be used ?
>>>
>>> BR Bo-Erik
>>>
>>>
>>>
>>> 2018-04-23 10:47 GMT+02:00 Hyunkook Lee :
>>>
>>> Indeed HIRT is the best IR capture package for Max.  There is also HAART,
>>>> which is a standalone Max application we developed using HIRT. This
>>>> software is all in one box for multichannel IR capture (24 mics x 24
>>>> sources), acoustic parameter analysis and binauralisation. The analysis
>>>> part is still under development, but the IR capture and binauralisation
>>>> parts are fully working. You can download it here
>>>>
>>>> http://eprints.hud.ac.uk/id/eprint/24579/
>>>>
>>>> Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel
>>>>
>>> mic
>>>
>>>> array configurations from stereo to 9ch 3D using HAART. The library
>>>> comes
>>>> with a Max renderer where you can convolve dry sources or signals fed
>>>>
>>> from
>>>
>>>> DAW with the mic array IRs for simultaneous comparisons between
>>>>
>>> techniques.
>>>
>>>>
>>>> https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer
>>>>
>>>> Best,
>>>> Hyunkook
>>>> =
>>>> Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
>>>> Senior Lecturer in Music Technology
>>>> Leader of the Applied Psychoacoustics Laboratory (APL)
>>>> http://www.hud.ac.uk/apl
>>>> http://www.hyunkooklee.com
>>>> Phone: +44 (0)1484 471893
>>>> Email: h@hud.ac.uk
>>>> Office: CE 2 /14a
>>>> School of Computing and Engineering
>>>> University of Huddersfield
>>>> Huddersfield
>>>> HD1 3DH
>>>> United Kingdom
>>>>
>>>> 
>>>> From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre
>>>> Alexandre Tremblay [tremb...@gmail.com]
>>>> Sent: 23 April 2018 09:29
>>>> To: Surround Sound discussion group
>>>> Subject: Re: [Sursound] RIR measuring, how to capture a higher order
>>>> Ambisonic room responce?
>>>>
>>>> If you use Max, try the very versatile HIRT.
>>>>
>>>> 2nd order with a tetramic is not possible as far as I am aware through…
>>>>
>>

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Fernando Lopez-Lezcano]

On 04/23/2018 04:24 AM, jack reynolds wrote:

The new coresound octomic is based on two tetramics, with one rotated 45
degrees from the other,


Hmm, does not look like that to me. If you, for example, take any two 
opposite capsules in the upper ring as part of one tetrahedral 
microphone, there are no capsules in the lower ring that would match the 
lower half of that microphone (they are rotated 45 degrees from where 
they should be).


-- Fernando


so if you could work out how the second order
B-format is extracted from the octomic array, you could potentially take an
A-format reponse with your tetramic, rotate the mic 45 degrees and capture
another, then process all eight channels?
Just a thought.

Jack

On 23 April 2018 at 11:51, Bo-Erik Sandholm  wrote:


Have never used Max, I need just 2, but probably 4 sound source positions
and one listening position.
But the listening position should have full spherical  ambisonic
soundfield.
But the result should be ambisonic IR's for these 4 sources.

The question is could upsampling be used ?

BR Bo-Erik



2018-04-23 10:47 GMT+02:00 Hyunkook Lee :


Indeed HIRT is the best IR capture package for Max.  There is also HAART,
which is a standalone Max application we developed using HIRT. This
software is all in one box for multichannel IR capture (24 mics x 24
sources), acoustic parameter analysis and binauralisation. The analysis
part is still under development, but the IR capture and binauralisation
parts are fully working. You can download it here

http://eprints.hud.ac.uk/id/eprint/24579/

Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel

mic

array configurations from stereo to 9ch 3D using HAART. The library comes
with a Max renderer where you can convolve dry sources or signals fed

from

DAW with the mic array IRs for simultaneous comparisons between

techniques.


https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer

Best,
Hyunkook
=
Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
Senior Lecturer in Music Technology
Leader of the Applied Psychoacoustics Laboratory (APL)
http://www.hud.ac.uk/apl
http://www.hyunkooklee.com
Phone: +44 (0)1484 471893
Email: h@hud.ac.uk
Office: CE 2 /14a
School of Computing and Engineering
University of Huddersfield
Huddersfield
HD1 3DH
United Kingdom


From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre
Alexandre Tremblay [tremb...@gmail.com]
Sent: 23 April 2018 09:29
To: Surround Sound discussion group
Subject: Re: [Sursound] RIR measuring, how to capture a higher order
Ambisonic room responce?

If you use Max, try the very versatile HIRT.

2nd order with a tetramic is not possible as far as I am aware through…

we

have done (mega)multimic IRs (24 channels of inputs, of which a 1st order
ambisonic) of 3 different spaces with our kit, and it was fun and
productive to train the ear on difference of multichannel mic techniques
(Hyunkook Lee has a cool setup and papers on them, and I was mostly
interested in DPA LCR omni vs coincident vs MS)

We did many stage positions too. I can investigate if I can share the
files if that interests anyone.

p



On 23 Apr 2018, at 08:37, Bo-Erik Sandholm 

wrote:


I want to measure the RIR of a medium size good listening room at least

up

to second order Ambisonic RIR.

The IR result is to incorporate the responce and reflections of the
speakers and their positions.

I have a tetramic.

Can several measurements and rotation of the tetra mic between them be
combined to create the measurements that comes closer to a second order

mic?


I know the basics of using Audacity, and a audio sweep and creating a

IR

from this.



Bo-Erik Sandholm
Stockholm
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Dave Hunt]

Hi,

As far as I know you cannot simply obtain 2nd order channels from two sets of 
1st order channels. A look at a visual representation of the spherical 
harmonics indicates that this is far from trivial.

https://brilliant.org/wiki/spherical-harmonics/

The SDM suggested by Archiontis, or Harpex may well use fairly complex 
mathematics to approximate a reasonable up-sample.

Ciao,

Dave Hunt


On 23 Apr 2018, at 17:00, sursound-requ...@music.vt.edu wrote:

> From: Politis Archontis 
> Subject: Re: [Sursound] RIR measuring, how to capture a higher order 
> Ambisonic room responce?
> Date: 23 April 2018 12:36:45 BST
> To: Surround Sound discussion group 
> 
> 
> Hi Bo-Erik,
> 
> if you use Matlab or Octave, you could also try the SDM method to upsample 
> from first-order RIRs to 2nd, 3rd, or any order you want basically. SDM 
> stands for the Spatial Decomposition Method from my colleague Sakari Tervo, 
> which has been used quite a lot for auralization and visualization of spatial 
> room IRs. You can find the toolbox available online.
> 
> HARPEX could potentially do it too, but since it is made for 
> reproduction/playback and most likely block processing, I don’t know if it 
> would cope well with the fine temporal structure of the RIR.
> 
> Regards,
> Archontis Politis

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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Politis Archontis]

Hi Bo-Erik,

if you use Matlab or Octave, you could also try the SDM method to upsample from 
first-order RIRs to 2nd, 3rd, or any order you want basically. SDM stands for 
the Spatial Decomposition Method from my colleague Sakari Tervo, which has been 
used quite a lot for auralization and visualization of spatial room IRs. You 
can find the toolbox available online.

HARPEX could potentially do it too, but since it is made for 
reproduction/playback and most likely block processing, I don’t know if it 
would cope well with the fine temporal structure of the RIR.

Regards,
Archontis Politis



On 23 Apr 2018, at 14:25, jack reynolds 
mailto:jackreynolds...@gmail.com>> wrote:

or yes, take a first order B-Format IR and upsample using Harpex is another
possibility.

J

On 23 April 2018 at 12:24, jack reynolds 
mailto:jackreynolds...@gmail.com>> wrote:

The new coresound octomic is based on two tetramics, with one rotated 45
degrees from the other, so if you could work out how the second order
B-format is extracted from the octomic array, you could potentially take an
A-format reponse with your tetramic, rotate the mic 45 degrees and capture
another, then process all eight channels?
Just a thought.

Jack

On 23 April 2018 at 11:51, Bo-Erik Sandholm 
mailto:bosses...@gmail.com>> wrote:

Have never used Max, I need just 2, but probably 4 sound source positions
and one listening position.
But the listening position should have full spherical  ambisonic
soundfield.
But the result should be ambisonic IR's for these 4 sources.

The question is could upsampling be used ?

BR Bo-Erik



2018-04-23 10:47 GMT+02:00 Hyunkook Lee 
mailto:h@hud.ac.uk>>:

Indeed HIRT is the best IR capture package for Max.  There is also
HAART,
which is a standalone Max application we developed using HIRT. This
software is all in one box for multichannel IR capture (24 mics x 24
sources), acoustic parameter analysis and binauralisation. The analysis
part is still under development, but the IR capture and binauralisation
parts are fully working. You can download it here

http://eprints.hud.ac.uk/id/eprint/24579/

Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel
mic
array configurations from stereo to 9ch 3D using HAART. The library
comes
with a Max renderer where you can convolve dry sources or signals fed
from
DAW with the mic array IRs for simultaneous comparisons between
techniques.

https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer

Best,
Hyunkook
=
Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
Senior Lecturer in Music Technology
Leader of the Applied Psychoacoustics Laboratory (APL)
http://www.hud.ac.uk/apl
http://www.hyunkooklee.com
Phone: +44 (0)1484 471893
Email: h@hud.ac.uk
Office: CE 2 /14a
School of Computing and Engineering
University of Huddersfield
Huddersfield
HD1 3DH
United Kingdom


From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre
Alexandre Tremblay [tremb...@gmail.com]
Sent: 23 April 2018 09:29
To: Surround Sound discussion group
Subject: Re: [Sursound] RIR measuring, how to capture a higher order
Ambisonic room responce?

If you use Max, try the very versatile HIRT.

2nd order with a tetramic is not possible as far as I am aware through…
we
have done (mega)multimic IRs (24 channels of inputs, of which a 1st
order
ambisonic) of 3 different spaces with our kit, and it was fun and
productive to train the ear on difference of multichannel mic techniques
(Hyunkook Lee has a cool setup and papers on them, and I was mostly
interested in DPA LCR omni vs coincident vs MS)

We did many stage positions too. I can investigate if I can share the
files if that interests anyone.

p


On 23 Apr 2018, at 08:37, Bo-Erik Sandholm 
mailto:bosses...@gmail.com>>
wrote:

I want to measure the RIR of a medium size good listening room at
least
up
to second order Ambisonic RIR.

The IR result is to incorporate the responce and reflections of the
speakers and their positions.

I have a tetramic.

Can several measurements and rotation of the tetra mic between them be
combined to create the measurements that comes closer to a second
order
mic?

I know the basics of using Audacity, and a audio sweep and creating a
IR
from this.



Bo-Erik Sandholm
Stockholm
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[jack reynolds]

or yes, take a first order B-Format IR and upsample using Harpex is another
possibility.

J

On 23 April 2018 at 12:24, jack reynolds  wrote:

> The new coresound octomic is based on two tetramics, with one rotated 45
> degrees from the other, so if you could work out how the second order
> B-format is extracted from the octomic array, you could potentially take an
> A-format reponse with your tetramic, rotate the mic 45 degrees and capture
> another, then process all eight channels?
> Just a thought.
>
> Jack
>
> On 23 April 2018 at 11:51, Bo-Erik Sandholm  wrote:
>
>> Have never used Max, I need just 2, but probably 4 sound source positions
>> and one listening position.
>> But the listening position should have full spherical  ambisonic
>> soundfield.
>> But the result should be ambisonic IR's for these 4 sources.
>>
>> The question is could upsampling be used ?
>>
>> BR Bo-Erik
>>
>>
>>
>> 2018-04-23 10:47 GMT+02:00 Hyunkook Lee :
>>
>> > Indeed HIRT is the best IR capture package for Max.  There is also
>> HAART,
>> > which is a standalone Max application we developed using HIRT. This
>> > software is all in one box for multichannel IR capture (24 mics x 24
>> > sources), acoustic parameter analysis and binauralisation. The analysis
>> > part is still under development, but the IR capture and binauralisation
>> > parts are fully working. You can download it here
>> >
>> > http://eprints.hud.ac.uk/id/eprint/24579/
>> >
>> > Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel
>> mic
>> > array configurations from stereo to 9ch 3D using HAART. The library
>> comes
>> > with a Max renderer where you can convolve dry sources or signals fed
>> from
>> > DAW with the mic array IRs for simultaneous comparisons between
>> techniques.
>> >
>> > https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer
>> >
>> > Best,
>> > Hyunkook
>> > =
>> > Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
>> > Senior Lecturer in Music Technology
>> > Leader of the Applied Psychoacoustics Laboratory (APL)
>> > http://www.hud.ac.uk/apl
>> > http://www.hyunkooklee.com
>> > Phone: +44 (0)1484 471893
>> > Email: h@hud.ac.uk
>> > Office: CE 2 /14a
>> > School of Computing and Engineering
>> > University of Huddersfield
>> > Huddersfield
>> > HD1 3DH
>> > United Kingdom
>> >
>> > 
>> > From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre
>> > Alexandre Tremblay [tremb...@gmail.com]
>> > Sent: 23 April 2018 09:29
>> > To: Surround Sound discussion group
>> > Subject: Re: [Sursound] RIR measuring, how to capture a higher order
>> > Ambisonic room responce?
>> >
>> > If you use Max, try the very versatile HIRT.
>> >
>> > 2nd order with a tetramic is not possible as far as I am aware through…
>> we
>> > have done (mega)multimic IRs (24 channels of inputs, of which a 1st
>> order
>> > ambisonic) of 3 different spaces with our kit, and it was fun and
>> > productive to train the ear on difference of multichannel mic techniques
>> > (Hyunkook Lee has a cool setup and papers on them, and I was mostly
>> > interested in DPA LCR omni vs coincident vs MS)
>> >
>> > We did many stage positions too. I can investigate if I can share the
>> > files if that interests anyone.
>> >
>> > p
>> >
>> >
>> > > On 23 Apr 2018, at 08:37, Bo-Erik Sandholm 
>> wrote:
>> > >
>> > > I want to measure the RIR of a medium size good listening room at
>> least
>> > up
>> > > to second order Ambisonic RIR.
>> > >
>> > > The IR result is to incorporate the responce and reflections of the
>> > > speakers and their positions.
>> > >
>> > > I have a tetramic.
>> > >
>> > > Can several measurements and rotation of the tetra mic between them be
>> > > combined to create the measurements that comes closer to a second
>> order
>> > mic?
>> > >
>> > > I know the basics of using Audacity, and a audio sweep and creating a
>> IR
>> > > from this.
>> > >
>> > >
>> > >
>> > > Bo-Erik Sandholm
>> > > Stockholm
>> > &g

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[jack reynolds]

The new coresound octomic is based on two tetramics, with one rotated 45
degrees from the other, so if you could work out how the second order
B-format is extracted from the octomic array, you could potentially take an
A-format reponse with your tetramic, rotate the mic 45 degrees and capture
another, then process all eight channels?
Just a thought.

Jack

On 23 April 2018 at 11:51, Bo-Erik Sandholm  wrote:

> Have never used Max, I need just 2, but probably 4 sound source positions
> and one listening position.
> But the listening position should have full spherical  ambisonic
> soundfield.
> But the result should be ambisonic IR's for these 4 sources.
>
> The question is could upsampling be used ?
>
> BR Bo-Erik
>
>
>
> 2018-04-23 10:47 GMT+02:00 Hyunkook Lee :
>
> > Indeed HIRT is the best IR capture package for Max.  There is also HAART,
> > which is a standalone Max application we developed using HIRT. This
> > software is all in one box for multichannel IR capture (24 mics x 24
> > sources), acoustic parameter analysis and binauralisation. The analysis
> > part is still under development, but the IR capture and binauralisation
> > parts are fully working. You can download it here
> >
> > http://eprints.hud.ac.uk/id/eprint/24579/
> >
> > Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel
> mic
> > array configurations from stereo to 9ch 3D using HAART. The library comes
> > with a Max renderer where you can convolve dry sources or signals fed
> from
> > DAW with the mic array IRs for simultaneous comparisons between
> techniques.
> >
> > https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer
> >
> > Best,
> > Hyunkook
> > =
> > Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
> > Senior Lecturer in Music Technology
> > Leader of the Applied Psychoacoustics Laboratory (APL)
> > http://www.hud.ac.uk/apl
> > http://www.hyunkooklee.com
> > Phone: +44 (0)1484 471893
> > Email: h@hud.ac.uk
> > Office: CE 2 /14a
> > School of Computing and Engineering
> > University of Huddersfield
> > Huddersfield
> > HD1 3DH
> > United Kingdom
> >
> > ________________________
> > From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre
> > Alexandre Tremblay [tremb...@gmail.com]
> > Sent: 23 April 2018 09:29
> > To: Surround Sound discussion group
> > Subject: Re: [Sursound] RIR measuring, how to capture a higher order
> > Ambisonic room responce?
> >
> > If you use Max, try the very versatile HIRT.
> >
> > 2nd order with a tetramic is not possible as far as I am aware through…
> we
> > have done (mega)multimic IRs (24 channels of inputs, of which a 1st order
> > ambisonic) of 3 different spaces with our kit, and it was fun and
> > productive to train the ear on difference of multichannel mic techniques
> > (Hyunkook Lee has a cool setup and papers on them, and I was mostly
> > interested in DPA LCR omni vs coincident vs MS)
> >
> > We did many stage positions too. I can investigate if I can share the
> > files if that interests anyone.
> >
> > p
> >
> >
> > > On 23 Apr 2018, at 08:37, Bo-Erik Sandholm 
> wrote:
> > >
> > > I want to measure the RIR of a medium size good listening room at least
> > up
> > > to second order Ambisonic RIR.
> > >
> > > The IR result is to incorporate the responce and reflections of the
> > > speakers and their positions.
> > >
> > > I have a tetramic.
> > >
> > > Can several measurements and rotation of the tetra mic between them be
> > > combined to create the measurements that comes closer to a second order
> > mic?
> > >
> > > I know the basics of using Audacity, and a audio sweep and creating a
> IR
> > > from this.
> > >
> > >
> > >
> > > Bo-Erik Sandholm
> > > Stockholm
> > > -- next part --
> > > An HTML attachment was scrubbed...
> > > URL: <https://mail.music.vt.edu/mailman/private/sursound/
> > attachments/20180423/ee496094/attachment.html>
> > > ___
> > > 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.
> >
> > ___
> > Sursound mailing list
> > Sursound@

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Bo-Erik Sandholm]

Have never used Max, I need just 2, but probably 4 sound source positions
and one listening position.
But the listening position should have full spherical  ambisonic soundfield.
But the result should be ambisonic IR's for these 4 sources.

The question is could upsampling be used ?

BR Bo-Erik



2018-04-23 10:47 GMT+02:00 Hyunkook Lee :

> Indeed HIRT is the best IR capture package for Max.  There is also HAART,
> which is a standalone Max application we developed using HIRT. This
> software is all in one box for multichannel IR capture (24 mics x 24
> sources), acoustic parameter analysis and binauralisation. The analysis
> part is still under development, but the IR capture and binauralisation
> parts are fully working. You can download it here
>
> http://eprints.hud.ac.uk/id/eprint/24579/
>
> Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel mic
> array configurations from stereo to 9ch 3D using HAART. The library comes
> with a Max renderer where you can convolve dry sources or signals fed from
> DAW with the mic array IRs for simultaneous comparisons between techniques.
>
> https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer
>
> Best,
> Hyunkook
> =
> Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
> Senior Lecturer in Music Technology
> Leader of the Applied Psychoacoustics Laboratory (APL)
> http://www.hud.ac.uk/apl
> http://www.hyunkooklee.com
> Phone: +44 (0)1484 471893
> Email: h@hud.ac.uk
> Office: CE 2 /14a
> School of Computing and Engineering
> University of Huddersfield
> Huddersfield
> HD1 3DH
> United Kingdom
>
> 
> From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre
> Alexandre Tremblay [tremb...@gmail.com]
> Sent: 23 April 2018 09:29
> To: Surround Sound discussion group
> Subject: Re: [Sursound] RIR measuring, how to capture a higher order
> Ambisonic room responce?
>
> If you use Max, try the very versatile HIRT.
>
> 2nd order with a tetramic is not possible as far as I am aware through… we
> have done (mega)multimic IRs (24 channels of inputs, of which a 1st order
> ambisonic) of 3 different spaces with our kit, and it was fun and
> productive to train the ear on difference of multichannel mic techniques
> (Hyunkook Lee has a cool setup and papers on them, and I was mostly
> interested in DPA LCR omni vs coincident vs MS)
>
> We did many stage positions too. I can investigate if I can share the
> files if that interests anyone.
>
> p
>
>
> > On 23 Apr 2018, at 08:37, Bo-Erik Sandholm  wrote:
> >
> > I want to measure the RIR of a medium size good listening room at least
> up
> > to second order Ambisonic RIR.
> >
> > The IR result is to incorporate the responce and reflections of the
> > speakers and their positions.
> >
> > I have a tetramic.
> >
> > Can several measurements and rotation of the tetra mic between them be
> > combined to create the measurements that comes closer to a second order
> mic?
> >
> > I know the basics of using Audacity, and a audio sweep and creating a IR
> > from this.
> >
> >
> >
> > Bo-Erik Sandholm
> > Stockholm
> > -- next part --
> > An HTML attachment was scrubbed...
> > URL: <https://mail.music.vt.edu/mailman/private/sursound/
> attachments/20180423/ee496094/attachment.html>
> > ___
> > 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.
>
> ___
> 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.
> University of Huddersfield inspiring tomorrow's professionals.
> [http://marketing.hud.ac.uk/_HOSTED/EmailSig2014/EmailSigFooter.jpg]
>
> This transmission is confidential and may be legally privileged. If you
> receive it in error, please notify us immediately by e-mail and remove it
> from your system. If the content of this e-mail does not relate to the
> business of the University of Huddersfield, then we do not endorse it and
> will accept no liability.
> ___
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Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Hyunkook Lee]

Indeed HIRT is the best IR capture package for Max.  There is also HAART, which 
is a standalone Max application we developed using HIRT. This software is all 
in one box for multichannel IR capture (24 mics x 24 sources), acoustic 
parameter analysis and binauralisation. The analysis part is still under 
development, but the IR capture and binauralisation parts are fully working. 
You can download it here

http://eprints.hud.ac.uk/id/eprint/24579/

Also as Pierre mentioned, we captured over 2000 IRs of 39 multichannel mic 
array configurations from stereo to 9ch 3D using HAART. The library comes with 
a Max renderer where you can convolve dry sources or signals fed from DAW with 
the mic array IRs for simultaneous comparisons between techniques.

https://github.com/APL-Huddersfield/MAIR-Library-and-Renderer

Best,
Hyunkook
=
Dr Hyunkook Lee, BMus(Tonmeister), PhD, MAES, FHEA
Senior Lecturer in Music Technology
Leader of the Applied Psychoacoustics Laboratory (APL)
http://www.hud.ac.uk/apl
http://www.hyunkooklee.com
Phone: +44 (0)1484 471893
Email: h@hud.ac.uk
Office: CE 2 /14a
School of Computing and Engineering
University of Huddersfield
Huddersfield
HD1 3DH
United Kingdom


From: Sursound [sursound-boun...@music.vt.edu] on behalf of Pierre Alexandre 
Tremblay [tremb...@gmail.com]
Sent: 23 April 2018 09:29
To: Surround Sound discussion group
Subject: Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic 
room responce?

If you use Max, try the very versatile HIRT.

2nd order with a tetramic is not possible as far as I am aware through… we have 
done (mega)multimic IRs (24 channels of inputs, of which a 1st order ambisonic) 
of 3 different spaces with our kit, and it was fun and productive to train the 
ear on difference of multichannel mic techniques (Hyunkook Lee has a cool setup 
and papers on them, and I was mostly interested in DPA LCR omni vs coincident 
vs MS)

We did many stage positions too. I can investigate if I can share the files if 
that interests anyone.

p


> On 23 Apr 2018, at 08:37, Bo-Erik Sandholm  wrote:
>
> I want to measure the RIR of a medium size good listening room at least up
> to second order Ambisonic RIR.
>
> The IR result is to incorporate the responce and reflections of the
> speakers and their positions.
>
> I have a tetramic.
>
> Can several measurements and rotation of the tetra mic between them be
> combined to create the measurements that comes closer to a second order mic?
>
> I know the basics of using Audacity, and a audio sweep and creating a IR
> from this.
>
>
>
> Bo-Erik Sandholm
> Stockholm
> -- next part --
> An HTML attachment was scrubbed...
> URL: 
> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20180423/ee496094/attachment.html>
> ___
> 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.

___
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Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit 
account or options, view archives and so on.
University of Huddersfield inspiring tomorrow's professionals.
[http://marketing.hud.ac.uk/_HOSTED/EmailSig2014/EmailSigFooter.jpg]

This transmission is confidential and may be legally privileged. If you receive 
it in error, please notify us immediately by e-mail and remove it from your 
system. If the content of this e-mail does not relate to the business of the 
University of Huddersfield, then we do not endorse it and will accept no 
liability.
___
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account or options, view archives and so on.

Re: [Sursound] RIR measuring, how to capture a higher order Ambisonic room responce?

[Pierre Alexandre Tremblay]

If you use Max, try the very versatile HIRT. 

2nd order with a tetramic is not possible as far as I am aware through… we have 
done (mega)multimic IRs (24 channels of inputs, of which a 1st order ambisonic) 
of 3 different spaces with our kit, and it was fun and productive to train the 
ear on difference of multichannel mic techniques (Hyunkook Lee has a cool setup 
and papers on them, and I was mostly interested in DPA LCR omni vs coincident 
vs MS)

We did many stage positions too. I can investigate if I can share the files if 
that interests anyone.

p


> On 23 Apr 2018, at 08:37, Bo-Erik Sandholm  wrote:
> 
> I want to measure the RIR of a medium size good listening room at least up
> to second order Ambisonic RIR.
> 
> The IR result is to incorporate the responce and reflections of the
> speakers and their positions.
> 
> I have a tetramic.
> 
> Can several measurements and rotation of the tetra mic between them be
> combined to create the measurements that comes closer to a second order mic?
> 
> I know the basics of using Audacity, and a audio sweep and creating a IR
> from this.
> 
> 
> 
> Bo-Erik Sandholm
> Stockholm
> -- next part --
> An HTML attachment was scrubbed...
> URL: 
> 
> ___
> 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.

___
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