Re: [PD] [OT] gallery installation sound

2007-02-13 Thread Frank Barknecht
Hallo,
Hans-Christoph Steiner hat gesagt: // Hans-Christoph Steiner wrote:

 Usually acoustic measurements are done with impulses, AFAIK.  An  
 ideal impulse actually has all frequencies in it, so it's useful for  
 that kind of thing.  Plus it's easy to differentiate between the  
 initial signal and the room effects just based on time.

Actually I think, engineers prefer to use frequency sweeps instead of
pulses nowadays. The problem with pulses is, that they are hard to get
right: You need a clean pulse and a very silent environment: 

   The main problem with using Dirac pulses in
   an acoustical measurement is that as a result of
   their very short duration and finite amplitude,
   they contain very little energy, and measure-
   ment accuracy will be limited by the signal to
   noise ratio of the equipment used and of the
   system itself. While it is possible to use Dirac
   pulses reproduced by a loudspeaker in the con-
   trolled environment of an acoustics laboratory,
   this is all but infeasible in most real life situa-
   tions, e.g. for measuring a room or concert hall,
   where there will always be background noises of
   some sort.

This is from Fons Adriaensen's LAC paper:
http://lac.zkm.de/2006/papers/lac2006_fons_adriaensen_01.pdf

Fons then explains sine sweeps as an alternative method: 

   The advantage of using a sweep is that at any
   time we produce only a single frequency, and
   any distortion introduced will consist of the har-
   monics of that frequency only. If we use a rising
   frequency sweep, the harmonics will be gener-
   ated ahead of the same frequencies appearing
   in the signal. So after deconvolution, any dis-
   tortion will appear as spurious peaks in negative
   time in the impulse response, and most of it can
   then be edited out easily.

This method's origin according to Fons is a paper by A. Farina:

  Angelo Farina. 2000. Simultanuous measurement of impulse response
  and distortion with a swept-sine technique. Audio Engineering
  Society Preprint 5093.

It is implementes in Fons' ALIKI software, that he presented at LAC2006.

Ciao
-- 
 Frank Barknecht _ __footils.org_ __goto10.org__

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Re: [PD] [OT] gallery installation sound

2007-02-13 Thread Malte Steiner


An excerpted acoustic study of an abandoned Soviet aircraft bunker. Max 
Borisov wears ear-mount binaural microphones, and I test the space with 
bricks and stones. Max and I found this technique very interesting, as 
it allows one person to literally become a human microphone, and the 


That is the good old Kunstkopfaufnahme (dummy head recording)

http://en.wikipedia.org/wiki/Dummy_head_recording

which is used for live-like live recordings

http://de.wikipedia.org/wiki/Binaurale_Tonaufnahme

in your case with a real head. I have to check out your recordings and 
place some stuff into the bunker :)


Cheers,

Malte
--
Malte Steiner
media art + development
-www.block4.com-

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Re: [PD] [OT] gallery installation sound

2007-02-13 Thread Kyle Klipowicz

That's a sweet concept, and a fun way to collaborate with active field
recording. I'll have to try that (giving you guys reference cred of
course)!

~Kyle

On 2/13/07, Derek Holzer [EMAIL PROTECTED] wrote:

I've used very rough impulse recordings to do binaural placement for
sounds--as well as pure abstract textures as Malte suggested--with very
nice results. See soundfiles and descriptions below from Karosta Project
(Latvia, 2002-3) http://karosta.edworks.net/

best,
d.

***

binaural.tunnel.study.1 [w/max.borisov][OGG 2min00sec 1.67Mb]
http://www.gracies.org/derek/audio/field.recordings.2/binaural.tunnel.study.1.ogg

An excerpted acoustic study of an abandoned Soviet aircraft bunker. Max
Borisov wears ear-mount binaural microphones, and I test the space with
bricks and stones. Max and I found this technique very interesting, as
it allows one person to literally become a human microphone, and the
other to perform for that audience/recorder [many thanks to Aaron Ximm
for inspiration in this and other matters]. A clever soul might use
these acoustic signatures to place other sounds in the same space
virtually...

***

Original Formanta EMS-01 Synthesizer improvisation [OGG 2min08sec 1.34Mb]
http://www.gracies.org/derek/audio/formanta.original.edit.ogg

Formanta.Drone [Surface.Noise] [OGG 7min10sec 4.92Mb]
http://www.gracies.org/derek/audio/formanta.drone.edit.ogg

The first is an excerpt of a live improvisation made on Maxim Borisov's
Formanta EMS-01 synthesizer. This is a big, nasty Russian synth that is
almost totally useless for melody, but has this amazing noise-driven Low
Frequency Oscillator with an array of filters behind it. All sounds on
the first track came only from this random sequencer, without laying a
finger on the keys. The second track resulted from a digital
cross-breeding with surface noise from an old Soviet marching
record--instant texture and depth!


--
derek holzer ::: http://www.umatic.nl
---Oblique Strategy # 160:
Towards the insignificant

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Re: [PD] [OT] gallery installation sound

2007-02-13 Thread Kyle Klipowicz

On 2/13/07, Frank Barknecht [EMAIL PROTECTED] wrote:

Actually I think, engineers prefer to use frequency sweeps instead of
pulses nowadays


How fast of a sweep are you talking about? Seconds or milliseconds? Is
this the 50 and 80 ms bit that the paper mentions?


  If we use a rising
  frequency sweep, the harmonics will be gener-
  ated ahead of the same frequencies appearing
  in the signal. So after deconvolution, any dis-
  tortion will appear as spurious peaks in negative
  time in the impulse response, and most of it can
  then be edited out easily.


What a great way to use an artifact of the FFT to one's advantage. Awesome!

~Kyle

--

http://theradioproject.com
http://perhapsidid.blogspot.com

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Re: [PD] [OT] gallery installation sound

2007-02-13 Thread Georg Holzmann

Hallo!

Usually acoustic measurements are done with impulses, AFAIK.  An  
ideal impulse actually has all frequencies in it, so it's useful for  
that kind of thing.  Plus it's easy to differentiate between the  
initial signal and the room effects just based on time.


Actually I think, engineers prefer to use frequency sweeps instead of
pulses nowadays. The problem with pulses is, that they are hard to get
right: You need a clean pulse and a very silent environment: 


Well, there are also problems with swept sines of course ... ;)

Other methods are e.g.
- with MLS (http://en.wikipedia.org/wiki/Maximum_length_sequence) - I 
think there is also an mls example in the iem_tab library.
-Least Square Error methods (see system identification example in the 
adaptive library)

- with noise (more energy than in a dirac impulse)
- auto-, crosscorrelation methods
- ...

LG
Georg


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Re: [PD] [OT] gallery installation sound

2007-02-08 Thread Kevin McCoy

Thank you all for your responses - each was very helpful!  I am particularly
interested (mostly out of curiosity) in how to measure the room with
convolution - would I blast some pink noise and then re-record it with a
good microphone, and then perform a frequency analysis on that?  I am sure I
can look this up somewhere.  Would this then yield the resonant frequencies
in the room?

Kevin

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Re: [PD] [OT] gallery installation sound

2007-02-08 Thread Frank Barknecht
Hallo,
Kevin McCoy hat gesagt: // Kevin McCoy wrote:

 Thank you all for your responses - each was very helpful!  I am particularly
 interested (mostly out of curiosity) in how to measure the room with
 convolution - would I blast some pink noise and then re-record it with a
 good microphone, and then perform a frequency analysis on that?  I am sure I
 can look this up somewhere.  Would this then yield the resonant frequencies
 in the room?

This nice paper may be interesting:
http://www.kokkinizita.net/linuxaudio/papers/aliki.pdf
http://www.kokkinizita.net/linuxaudio/index.html

Ciao
-- 
 Frank Barknecht _ __footils.org_ __goto10.org__

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Re: [PD] [OT] gallery installation sound

2007-02-07 Thread David Powers

On 2/7/07, Kevin McCoy [EMAIL PROTECTED] wrote:
there are many sound scientists and artists on the list so I thought

I would ask if anyone knows of resources to look at for dealing with these
kinds of issues?  How are other artists sorting these things out?  Any links
or recommendations would be very helpful.  Low ends tend to get very muddy
and the highs and mids spill all over the place.  Are there certain tricks I
could use in mixing or placement/kinds of speakers to preserve the highs and
mids better in a difficult space?  This might be a difficult question since
you can't hear the piece in person, but even general advice would be very
helpful.


I'm no sound scientist, but wouldn't just some ordinary foam of the
type people put in their music studios help? It sounds like you are
having trouble with unwanted and weird reverberations, which the foam
should lesson. Having performed music in such spaces (concrete and
metal), I've got a pretty good idea of the kind of acoustic nightmare
you are probably facing...

~David

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Re: [PD] [OT] gallery installation sound

2007-02-07 Thread Ben Saylor
I haven't done any sound installations, but in thinking about a 
particular space had some ideas for dealing with these acoustical 
issues.  You could design the sound for the space, working with rather 
than against the acoustics.  If possible, you could capture the impulse 
response of the space (perhaps in multiple locations), then as you work 
on the sound, use convolution to hear how it will sound in the space.  I 
guess the degree to which you can adapt your piece depends on how far 
along you already are.


Alternatively, you could acoustically treat the space using acoustic 
foam or rigid fiberglass.  This page has tons of good info:


http://www.ethanwiner.com/acoustics.html

Ben

Kevin McCoy wrote:

Hello all,

Apologies for the ot post; I've got my final thesis show coming up in 
early April and I'm doing all sound work using Pd.  The gallery space I 
am using is actually quite poor for acoustics, as it's got a concrete 
floor and metal roofing.  It's relatively small though - two hallways 
each about 10 feet by 30 feet large (3 by 9 meters if you like) making a 
T shape.  I would like to do two 4 channel sound installations, 
perhaps one for each hallway.


I know there are many sound scientists and artists on the list so I 
thought I would ask if anyone knows of resources to look at for dealing 
with these kinds of issues?  How are other artists sorting these things 
out?  Any links or recommendations would be very helpful.  Low ends tend 
to get very muddy and the highs and mids spill all over the place.  Are 
there certain tricks I could use in mixing or placement/kinds of 
speakers to preserve the highs and mids better in a difficult space?  
This might be a difficult question since you can't hear the piece in 
person, but even general advice would be very helpful.


Also if any of you have documentation of your own installations, I would 
love to see them.


Thanks!
Kevin

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http://pocketkm.blogspot.com http://pocketkm.blogspot.com




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Re: [PD] [OT] gallery installation sound

2007-02-07 Thread Charles Henry

If you can (and it's a big if), try to suspend your acoustic dampening
panels above the heads of people.  This will have a big effect on your
reverb problems without disrupting the space in the hallway.

I like the suggestions on this thread.  very insightful

Chuck

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Re: [PD] [OT] gallery installation sound

2007-02-07 Thread Chuckk Hubbard

We went to the Kimmel Center last semester in acoustics class, and
this is exactly what they do.  They have a huge foil on top that they
raise or lower depending on the size of the ensemble.  Now, they also
have huge empty wells on both sides of the auditorium, and if they
need wider reverb they open these huge walls in the auditorium so the
sound can go all around- but I'm guessing that's beyond your means.

I also like the impulse response idea, if nothing else you can learn
from doing it.
The only thing I can add is that if you try delaying the sound at one
end of the room, you can make people feel like the sound is coming
from the other end; then, maybe, they'll move towards that end and get
more direct sound.

-Chuckk


On 2/7/07, Charles Henry [EMAIL PROTECTED] wrote:

If you can (and it's a big if), try to suspend your acoustic dampening
panels above the heads of people.  This will have a big effect on your
reverb problems without disrupting the space in the hallway.

I like the suggestions on this thread.  very insightful

Chuck

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