i have a pair of JBL monitors that, through the use of an 

omnidirectional mic placed at the listening point and connected to the 

speakers, perform a room mode adjustment via some sine sweeps. i am 

assuming that spectral analysis of the sweeps allow the monitors to 

determine what frequencies a space amplifies or attenuates, and it 

i'm wondering if anyone on this list has done anything similar with 

Max/MSP? So, assuming you have a two monitor (or PA speaker) setup with 

an omnidirectional mic placed at some predetermined distance from the 

speakers, how would you determine the standing waves in a given space 

(automatically - that is an important caveat)? if you have done this but 

with another tool, i'd be curious to hear about it, but i plan on 

one approach i have considered is playing a sine sweep out the monitors, 

recording it, then playing that recording back and recording it, and 

over again several times, until the amplified/attenuated frequencies 

really start to stand out. then compare FFTs of generation 1 with 

generation 5 (or something like that) and look for the significant 

differences. anyway, i'm interested and curious to hear ideas, input, 

criticisms, etc. this project is to end in an installation as part of my 

dissertation, so all code developed for it will be shared and open. many 

i have a pair of JBL monitors that, through the use of an 
omnidirectional mic placed at the listening point and connected to the 
speakers, perform a room mode adjustment via some sine sweeps. i am 
assuming that spectral analysis of the sweeps allow the monitors to 
determine what frequencies a space amplifies or attenuates, and it 
adjusts it's eq accordingly.

i'm wondering if anyone on this list has done anything similar with 
Max/MSP? So, assuming you have a two monitor (or PA speaker) setup with 
an omnidirectional mic placed at some predetermined distance from the 
speakers, how would you determine the standing waves in a given space 
(automatically - that is an important caveat)? if you have done this but 
with another tool, i'd be curious to hear about it, but i plan on 
implementing it in Max myself.

one approach i have considered is playing a sine sweep out the monitors, 
recording it, then playing that recording back and recording it, and 
over again several times, until the amplified/attenuated frequencies 
really start to stand out. then compare FFTs of generation 1 with 
generation 5 (or something like that) and look for the significant 
differences. anyway, i'm interested and curious to hear ideas, input, 
criticisms, etc. this project is to end in an installation as part of my 
dissertation, so all code developed for it will be shared and open. many 
thanks in advance.

room-mode-detection-with-max

I never tried this, but I would definitely use only one speaker to play the sine to avoid an unnecessary risk of interference at the position of the mic.

yes, i'm doing that. i made some recordings of the Room Mode Correction 

sequence that my JBLs do, and they don't seem to put out simple sine 

sweeps. this is also possibly because they are calibrating purely for 

the listening position. for my purposes, i don't care a specific 

listening position, but rather just determining the standing 

> I never tried this, but I would definitely use only one speaker to play the sine to avoid an unnecessary risk of interference at the position of the mic.

yes, i'm doing that. i made some recordings of the Room Mode Correction 
sequence that my JBLs do, and they don't seem to put out simple sine 
sweeps. this is also possibly because they are calibrating purely for 
the listening position. for my purposes, i don't care a specific 
listening position, but rather just determining the standing 
waves/harmonics of a space.

Mattijs Kneppers wrote:
> I never tried this, but I would definitely use only one speaker to play the sine to avoid an unnecessary risk of interference at the position of the mic.
>
> Mattijs
>


I would say take the recording of the sine sweeps (first find out what pitch range the sine sweep has-and what exact pitches occur at say, 64 points of the sine sweep) and then subtract the dry (not played back through the room, internal) sine sweep to find out what the room adds to the sound, and at what pitches the room amplifies the sine sweep at. 

Then with that information send all of Max/MSPs output through a [filtergraph~] object that EQs the Max/MSP audio accordingly, before it is outputted into the room.

I would say take the recording of the sine sweeps (first find out what pitch range the sine sweep has-and what exact pitches occur at say, 64 points of the sine sweep) and then subtract the dry (not played back through the room, internal) sine sweep to find out what the room adds to the sound, and at what pitches the room amplifies the sine sweep at. 
Then with that information send all of Max/MSPs output through a [filtergraph~] object that EQs the Max/MSP audio accordingly, before it is outputted into the room.


But isn't the best way to characterize a room to simply get its impulse response? This would automatically give you the frequency response.

Quote: pmt4u wrote on Fri, 06 June 2008 18:49

----------------------------------------------------

> yes, i'm doing that. i made some recordings of the Room Mode Correction 

> sequence that my JBLs do, and they don't seem to put out simple sine 

> sweeps. this is also possibly because they are calibrating purely for 

> the listening position. for my purposes, i don't care a specific 

> listening position, but rather just determining the standing 

> > I never tried this, but I would definitely use only one speaker to play the sine to avoid an unnecessary risk of interference at the position of the mic.

Quote: pmt4u wrote on Fri, 06 June 2008 18:49
----------------------------------------------------
> yes, i'm doing that. i made some recordings of the Room Mode Correction 
> sequence that my JBLs do, and they don't seem to put out simple sine 
> sweeps. this is also possibly because they are calibrating purely for 
> the listening position. for my purposes, i don't care a specific 
> listening position, but rather just determining the standing 
> waves/harmonics of a space.
>
> p
>
> Mattijs Kneppers wrote:
> > I never tried this, but I would definitely use only one speaker to play the sine to avoid an unnecessary risk of interference at the position of the mic.
> >
> > Mattijs
> >
>
>
----------------------------------------------------


On Jun 6, 2008, at 2:40 PM, Mattijs Kneppers wrote:

> But isn't the best way to characterize a room to simply get its 

> impulse response? This would automatically give you the frequency 

But would this tell you much about standing waves?

On Jun 6, 2008, at 2:40 PM, Mattijs Kneppers wrote:
> But isn't the best way to characterize a room to simply get its  
> impulse response? This would automatically give you the frequency  
> response.

Chris Muir
cbm@well.com	
http://www.xfade.com

http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html

this might help:
http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html


i thought about trying an impulse too, but haven't gotten to it yet. my 

guess is that i would need to do several record/play sequences to build 

up enough response that the standing frequencies could be detected 

automatically. another method i tried last night was just playing a few 

seconds of white noise (using noise~ of course), and record/playing 

several times over. that also brought out specific frequencies over 

time, although i'm not quite sure yet how to actually determine those 

frequencies via analysis in max (i haven't used the fft objects before, 

but i'm guessing that is where the answers lie). still, a sine sweep 

seems to produce the best results so far.

> On Jun 6, 2008, at 2:40 PM, Mattijs Kneppers wrote:

>> But isn't the best way to characterize a room to simply get its 

>> impulse response? This would automatically give you the frequency 

> But would this tell you much about standing waves?

i thought about trying an impulse too, but haven't gotten to it yet. my 
guess is that i would need to do several record/play sequences to build 
up enough response that the standing frequencies could be detected 
automatically. another method i tried last night was just playing a few 
seconds of white noise (using noise~ of course), and record/playing 
several times over. that also brought out specific frequencies over 
time, although i'm not quite sure yet how to actually determine those 
frequencies via analysis in max (i haven't used the fft objects before, 
but i'm guessing that is where the answers lie). still, a sine sweep 
seems to produce the best results so far.

Chris Muir wrote:
>
> On Jun 6, 2008, at 2:40 PM, Mattijs Kneppers wrote:
>> But isn't the best way to characterize a room to simply get its 
>> impulse response? This would automatically give you the frequency 
>> response.
>
>
> But would this tell you much about standing waves?
>
> -C
>
> Chris Muir
> cbm@well.com   
> http://www.xfade.com
>
>
>
>
>
>


this is useful, although i'm not sure if it is in terms of what i'm 

trying to accomplish in this particular patch. the issue here is that it 

should be an automated process, i.e., that the software should be able 

to sound out the fundamental modes of the room, and then use them to 

musical effect later on. this means it knows nothing about the space's 

actual dimensions. this is still nice tool though, thanks!

this is useful, although i'm not sure if it is in terms of what i'm 
trying to accomplish in this particular patch. the issue here is that it 
should be an automated process, i.e., that the software should be able 
to sound out the fundamental modes of the room, and then use them to 
musical effect later on. this means it knows nothing about the space's 
actual dimensions. this is still nice tool though, thanks!

Klaas-Jan Govaart wrote:
> this might help:
> http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html
>


Yes, you're going to have to analyze the recorded sine sweep or impulse with the Fast Fourier Transform, so get comfortable with the objects that use it.

a quick and dirty way to do this is to record the ambient sound of the

room then play it back into the room, then record that, and play it,

then record that, then play it... etc. It is a rough way of doing it

and any attenuations and boosts in your speaker or mic might influence

the result but it is a quick way to get some of the stronger room

On Sat, Jun 7, 2008 at 2:37 AM, Eli Stine wrote:

> Yes, you're going to have to analyze the recorded sine sweep or impulse with the Fast Fourier Transform, so get comfortable with the objects that use it.

a quick and dirty way to do this is to record the ambient sound of the
room then play it back into the room, then record that, and play it,
then record that, then play it... etc.  It is a rough way of doing it
and any attenuations and boosts in your speaker or mic might influence
the result but it is a quick way to get some of the stronger room
modes and it is a fun experiment :)

On Sat, Jun 7, 2008 at 2:37 AM, Eli Stine  wrote:
>
> Yes, you're going to have to analyze the recorded sine sweep or impulse with the Fast Fourier Transform, so get comfortable with the objects that use it.
>


So you want Max to detect the room modes. Ok.

Guess I was skipping through your original message a bit too fast yesterday. I thought you just wanted to know (through whatever means) what the modes of the room are. The math behind that isn't really that hard, so I figured you could just calculate it instead of using a patch measuring. When trying to dig out the formulas I ran into the applet that does in for you.

I guess sweeping the room could get you some data on the dips and peaks (but at the exact mic position only!). I'm assuming you would want to correct for those using eq? Keep in mind that a peak in one spot (near a node) often has a corresponding dip (near the anti-node) ans vice versa. 

Say you measure -3dB at 100Hz where your mic is.. Then you set up an eq to compensate for that.. In another place in the room, you have now increased a 3db peak at 100Hz to 6dB. (Simplified example, but you get the idea).

Keep in mind that using a sine sweep through one speaker is only a very rough approximation of the real life situation. With two speakers and complex sound, moving the microphone only an inch can result in a very different measurement. Prepare to lock your head using some metal.. You need to be in a fixed position...

Also, room modes are not only a frequency, but also a time domain issue.. They are resonances - stored energy. Read into modal ringing.

I feel that eq/filtering is not the way of dealing with problems in acoustics, generally. Money spent of speakers and plugins that provide "corrective" systems, is often better spent on a bass trap or two... After doing some calculations, of course. This way you deal with the problem at the source. "Corrections" using filtering and such are just a band-aid.

What is your application?? Or is it just about "can I built the same thing in Max?", regardless of it being a good way of dealing with things or not?

Quote: pmt4u wrote on Sat, 07 June 2008 03:05

> this is useful, although i'm not sure if it is in terms of what i'm 

> trying to accomplish in this particular patch. the issue here is that it 

> should be an automated process, i.e., that the software should be able 

> to sound out the fundamental modes of the room, and then use them to 

> musical effect later on. this means it knows nothing about the space's 

> actual dimensions. this is still nice tool though, thanks!

So you want Max to detect the room modes. Ok.
Guess I was skipping through your original message a bit too fast yesterday. I thought you just wanted to know (through whatever means) what the modes of the room are. The math behind that isn't really that hard, so I figured you could just calculate it instead of using a patch measuring. When trying to dig out the formulas I ran into the applet that does in for you.

I guess sweeping the room could get you some data on the dips and peaks (but at the exact mic position only!). I'm assuming you would want to correct for those using eq? Keep in mind that a peak in one spot (near a node) often has a corresponding dip (near the anti-node) ans vice versa. 
Say you measure -3dB at 100Hz where your mic is.. Then you set up an eq to compensate for that.. In another place in the room, you have now increased a 3db peak at 100Hz to 6dB. (Simplified example, but you get the idea).
Keep in mind that using a sine sweep through one speaker is only a very rough approximation of the real life situation. With two speakers and complex sound, moving the microphone only an inch can result in a very different measurement. Prepare to lock your head using some metal.. You need to be in a fixed position...
Also, room modes are not only a frequency, but also a time domain issue.. They are resonances - stored energy. Read into modal ringing.

What is your application?? Or is it just about "can I built the same thing in Max?", regardless of it being a good way of dealing with things or not? 

Quote: pmt4u wrote on Sat, 07 June 2008 03:05
----------------------------------------------------
> this is useful, although i'm not sure if it is in terms of what i'm 
> trying to accomplish in this particular patch. the issue here is that it 
> should be an automated process, i.e., that the software should be able 
> to sound out the fundamental modes of the room, and then use them to 
> musical effect later on. this means it knows nothing about the space's 
> actual dimensions. this is still nice tool though, thanks!
>
> p
>
> Klaas-Jan Govaart wrote:
> > this might help:
> > http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html
> >
>
>
----------------------------------------------------


thanks! i was wondering how much of a difference mic position would 

make. i figured it would make a lot, thanks for confirming that. in 

terms of my application, i'm not actually looking to eq/filter at all. 

this is for a piece, a sort of automated sound installation that could 

be placed in any enclosed space, sound out the space, and then play with 

the resonances/modes it detects. so i'm really looking to play with and 

exploit those modes, rather than filtering them out or compensating for 

them. my jbl monitors obviously do this analysis as a form of 

correction, which gave me the idea to use a similar technique for a 

> So you want Max to detect the room modes. Ok.

> Guess I was skipping through your original message a bit too fast yesterday. I thought you just wanted to know (through whatever means) what the modes of the room are. The math behind that isn't really that hard, so I figured you could just calculate it instead of using a patch measuring. When trying to dig out the formulas I ran into the applet that does in for you.

> I guess sweeping the room could get you some data on the dips and peaks (but at the exact mic position only!). I'm assuming you would want to correct for those using eq? Keep in mind that a peak in one spot (near a node) often has a corresponding dip (near the anti-node) ans vice versa. 

> Say you measure -3dB at 100Hz where your mic is.. Then you set up an eq to compensate for that.. In another place in the room, you have now increased a 3db peak at 100Hz to 6dB. (Simplified example, but you get the idea).

> Keep in mind that using a sine sweep through one speaker is only a very rough approximation of the real life situation. With two speakers and complex sound, moving the microphone only an inch can result in a very different measurement. Prepare to lock your head using some metal.. You need to be in a fixed position...

> Also, room modes are not only a frequency, but also a time domain issue.. They are resonances - stored energy. Read into modal ringing.

> I feel that eq/filtering is not the way of dealing with problems in acoustics, generally. Money spent of speakers and plugins that provide "corrective" systems, is often better spent on a bass trap or two... After doing some calculations, of course. This way you deal with the problem at the source. "Corrections" using filtering and such are just a band-aid.

> What is your application?? Or is it just about "can I built the same thing in Max?", regardless of it being a good way of dealing with things or not? 

> Quote: pmt4u wrote on Sat, 07 June 2008 03:05

> ----------------------------------------------------

>> this is useful, although i'm not sure if it is in terms of what i'm 

>> trying to accomplish in this particular patch. the issue here is that it 

>> should be an automated process, i.e., that the software should be able 

>> to sound out the fundamental modes of the room, and then use them to 

>> musical effect later on. this means it knows nothing about the space's 

>> actual dimensions. this is still nice tool though, thanks!

thanks! i was wondering how much of a difference mic position would 
make. i figured it would make a lot, thanks for confirming that. in 
terms of my application, i'm not actually looking to eq/filter at all. 
this is for a piece, a sort of automated sound installation that could 
be placed in any enclosed space, sound out the space, and then play with 
the resonances/modes it detects. so i'm really looking to play with and 
exploit those modes, rather than filtering them out or compensating for 
them. my jbl monitors obviously do this analysis as a form of 
correction, which gave me the idea to use a similar technique for a 
difference purpose.

Klaas-Jan Govaart wrote:
> So you want Max to detect the room modes. Ok.
> Guess I was skipping through your original message a bit too fast yesterday. I thought you just wanted to know (through whatever means) what the modes of the room are. The math behind that isn't really that hard, so I figured you could just calculate it instead of using a patch measuring. When trying to dig out the formulas I ran into the applet that does in for you.
>
> I guess sweeping the room could get you some data on the dips and peaks (but at the exact mic position only!). I'm assuming you would want to correct for those using eq? Keep in mind that a peak in one spot (near a node) often has a corresponding dip (near the anti-node) ans vice versa. 
> Say you measure -3dB at 100Hz where your mic is.. Then you set up an eq to compensate for that.. In another place in the room, you have now increased a 3db peak at 100Hz to 6dB. (Simplified example, but you get the idea).
> Keep in mind that using a sine sweep through one speaker is only a very rough approximation of the real life situation. With two speakers and complex sound, moving the microphone only an inch can result in a very different measurement. Prepare to lock your head using some metal.. You need to be in a fixed position...
> Also, room modes are not only a frequency, but also a time domain issue.. They are resonances - stored energy. Read into modal ringing.
>
> I feel that eq/filtering is not the way of dealing with problems in acoustics, generally. Money spent of speakers and plugins that provide "corrective" systems, is often better spent on a bass trap or two... After doing some calculations, of course. This way you deal with the problem at the source. "Corrections" using filtering and such are just a band-aid.
>
> What is your application?? Or is it just about "can I built the same thing in Max?", regardless of it being a good way of dealing with things or not? 
>
> regards,
> kjg
>
>
>
> Quote: pmt4u wrote on Sat, 07 June 2008 03:05
> ----------------------------------------------------
>
>> this is useful, although i'm not sure if it is in terms of what i'm 
>> trying to accomplish in this particular patch. the issue here is that it 
>> should be an automated process, i.e., that the software should be able 
>> to sound out the fundamental modes of the room, and then use them to 
>> musical effect later on. this means it knows nothing about the space's 
>> actual dimensions. this is still nice tool though, thanks!
>>
>> p
>>
>> Klaas-Jan Govaart wrote:
>>
>>> this might help:
>>> http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html
>>>
>>>
>>
> ----------------------------------------------------
>
>
>


Quote: pmt4u wrote on Sat, 07 June 2008 16:44

> thanks! i was wondering how much of a difference mic position would 

> make. i figured it would make a lot, thanks for confirming that. in 

> terms of my application, i'm not actually looking to eq/filter at all. 

> this is for a piece, a sort of automated sound installation that could 

> be placed in any enclosed space, sound out the space, and then play with 

> the resonances/modes it detects. so i'm really looking to play with and 

> exploit those modes, rather than filtering them out or compensating for 

> them. my jbl monitors obviously do this analysis as a form of 

> correction, which gave me the idea to use a similar technique for a 

ok, sounds interesting! keep us posted on your progress, ok?

Quote: pmt4u wrote on Sat, 07 June 2008 16:44
----------------------------------------------------
> thanks! i was wondering how much of a difference mic position would 
> make. i figured it would make a lot, thanks for confirming that. in 
> terms of my application, i'm not actually looking to eq/filter at all. 
> this is for a piece, a sort of automated sound installation that could 
> be placed in any enclosed space, sound out the space, and then play with 
> the resonances/modes it detects. so i'm really looking to play with and 
> exploit those modes, rather than filtering them out or compensating for 
> them. my jbl monitors obviously do this analysis as a form of 
> correction, which gave me the idea to use a similar technique for a 
> difference purpose.

ok, sounds interesting! keep us posted on your progress, ok? 

hi, i read this post and is a realy interesting subject, but, instead of using fft why don't simple use analyze~ ?? i'm i going to a wrong way?

thanks luis, i'll check it out. currently cnmat.berkeley.edu (where the 

object is apparently hosted) is not responding for me, so hopefully 

they'll bring it back online soon. i'll let you know if analyzer~ does 

> hi, i read this post and is a realy interesting subject, but, instead of using fft why don't simple use analyze~ ?? i'm i going to a wrong way?

thanks luis, i'll check it out. currently cnmat.berkeley.edu (where the 
object is apparently hosted) is not responding for me, so hopefully 
they'll bring it back online soon. i'll let you know if analyzer~ does 
what i'm looking for. thanks again.

Luis Marques wrote:
> hi, i read this post and is a realy interesting subject, but, instead of using fft why don't simple use analyze~ ?? i'm i going to a wrong way?
>


i can send it to you, or post a link here... just let me know.

that would be great. either emailing to me or posting a link on the list 

is fine. the cnmat site is still currently down (at least from where i'm 

trying to reach it). i need the OSX version of the external. thanks luis!

> i can send it to you, or post a link here... just let me know.

that would be great. either emailing to me or posting a link on the list 
is fine. the cnmat site is still currently down (at least from where i'm 
trying to reach it). i need the OSX version of the external. thanks luis!

Luis Marques wrote:
> i can send it to you, or post a link here... just let me know.
>


ok, below is the rapidshare link, since you mention CNMAT i presume you want the whole package. just let me know if analyze~ is the answer.

http://rapidshare.com/files/121246903/CNMAT-MachO.zip.html

ok, below is the rapidshare link, since you mention CNMAT i presume you want the whole package. just let me know if analyze~ is the answer.
http://rapidshare.com/files/121246903/CNMAT-MachO.zip.html


i forgot to mention, this is the mac osx package and i tested in max 4.6.3 and 5.0.2 and works fine. i presume this works on windows too, but in not shure, since i only work whit mac.

thank you again luis, this is great. as far as platforms go, tristan 

jehan provides separate binaries for win, os9, and osX on his site, so 

i'm not sure these ones would work on anything other than a mac running 

os x. anyway, i'll get to work learning about them, and will update the 

list if i come up with any interesting/working solutions to my problem. 

> i forgot to mention, this is the mac osx package and i tested in max 4.6.3 and 5.0.2 and works fine. i presume this works on windows too, but in not shure, since i only work whit mac. 

thank you again luis, this is great. as far as platforms go, tristan 
jehan provides separate binaries for win, os9, and osX on his site, so 
i'm not sure these ones would work on anything other than a mac running 
os x. anyway, i'll get to work learning about them, and will update the 
list if i come up with any interesting/working solutions to my problem. 
many thanks again for your help.

Luis Marques wrote:
> i forgot to mention, this is the mac osx package and i tested in max 4.6.3 and 5.0.2 and works fine. i presume this works on windows too, but in not shure, since i only work whit mac. 
>


Room mode detection with Max