Room too dead???

Post and discuss acoustic topics, Studio design, construction, and soundproofing here

Postby bert stoltenborg » Wed Jul 06, 2005 12:25 am

Hey Eric,

Thanks, but I guess Fitz didn't mean it that bad.
When he follows this forum he knows that we try to cover the extremes in science, and because we know that's an almost  hopeless task we now and then take refugee to stupid humor.

In fact we very often take refugee to very stupid humor  :mrgreen:  :mrgreen:  :mrgreen:
It takes a Belg, a stupid dutchman, an Israeli, an rumenian, a portugesian, a swiss guy, a couple of  guys from england, some canadians (trashcan :-))  and  yankees (is Fargo yankee county, Brian?  :-)) and do I know who to value this bunch of nonsense, and when you can distinguish between stupidity and value this must be one of the best forums, even when I'm on it now and then.... The experts/nice guys from other forums like Steve and Rod and David etc are here now and then to correct us, aren't they?
When you can't make these differences there are other forums with absolute answers to every question.

:mrgreen:  :mrgreen:  :mrgreen:

Het Bertje

Our lead singer has cut my hair, so Ido, no more long hair, only moderate long hair.
:mrgreen:
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Postby bert stoltenborg » Wed Jul 06, 2005 12:32 am

Eric.Desart wrote:i can handle the forum.

please stick to content or being the bunch of friends (even when different or disagreeing) we're supposed to be.


Yeah,

Let's take this for what it is: a friendly bunch of guys (no women!    :mrgreen: ) making fun trying to learn one or two things about sound.
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Postby Eric.Desart » Wed Jul 06, 2005 2:04 am

bert stoltenborg wrote:this must be one of the best forums, even when I'm on it now and then....
:mrgreen:  :mrgreen:  :mrgreen:
Het Bertje


:)  nothing can be perfect .....
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Postby avare » Wed Jul 06, 2005 2:28 pm

I am going to get this right this time!

The EBU, NOT ITU doc on listening envirinmnets that is online is "EBU Tech. 3276 – 2nd edition".

The URL to ti is:


http://www.ebu.ch/CMSimages/en/tec_doc_t3276_tcm6-10536.pdf

There are other sound related docs from the EBU listed here:

http://www.ebu.ch/en/technical/publications/tech3000_series/index.php#1


The tonmeister doc is  "RECOMMENDED PRACTICE SSF – 01.1- E-2002"

The URL is:

http://www.tonmeister.de/foren/surround/texte/SSF_01_1_E_2002_v2a.PDF


I hope I have these right finally!

Andre
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Postby J.F.Oros » Wed Jul 06, 2005 2:31 pm

bert stoltenborg wrote:It takes a Belg, a stupid dutchman, an Israeli, an rumenian...

Now you misspelled my name  :evil: : it's romanian  :mrgreen:


Our lead singer has cut my hair, so Ido, no more long hair, only moderate long hair.
:mrgreen:

It's probably the new look of the OT-trio, because :

The OT-bass player some time ago:

Image

...and now:

Image

Now we just have to find the early-years, long-hair Eric photos!  :roll:  
:mrgreen:
... studiOTipper ...
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Postby Eric.Desart » Wed Jul 06, 2005 2:48 pm

edited:  :oops:  improving my live, removed pictures


andre: many thanks for those links
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Postby Paul Woodlock » Wed Jul 06, 2005 3:28 pm

bert stoltenborg wrote:Hey Eric,

Thanks, but I guess Fitz didn't mean it that bad.
When he follows this forum he knows that we try to cover the extremes in science, and because we know that's an almost  hopeless task we now and then take refugee to stupid humor.

In fact we very often take refugee to very stupid humor  :mrgreen:  :mrgreen:  :mrgreen:
...


The World NEEDS more STUPID HUMOUR!!!!

:D :D :D :D
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Postby J.F.Oros » Wed Jul 06, 2005 4:03 pm

Eric.Desart wrote:edited:  :oops:  improving my live, removed pictures

I was just going to say that the first ONE sings and the second ONE must be the drummer  :D
... studiOTipper ...
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Postby avare » Wed Jul 06, 2005 5:42 pm

Bob:

Measurable characteristics from the docs, but not certain if ETF does them:

- decay rate
- decay rate frequency dependence and fitting the mask
- sytem flatness
- system matching
- noise level
- (lack of) flutter echoes

I this helps.

Eric:

Thanks for the thanks.  I know I have referenced all those documents in the past, but thought it best to repeat the URLS again. :)

Andre
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Postby andrebrito » Wed Jul 06, 2005 11:57 pm

Hey bert, what is a portuguesian ? a portuguese with asian traces ?

:-)


Gee, what a mess because I said I recommended a RT of 0.5 s for a recording room...  I know  RT60 is not reliable measurement for a  small room.

But it maybe a starting point , imagine you check the Schoroeder plot and most extraplated RT60 curves assume a value of 0.1 s , won't that be an indication the room is too dead ?
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Postby bert stoltenborg » Thu Jul 07, 2005 9:39 am

andrebrito wrote:Hey bert, what is a portuguesian ? a portuguese with asian traces ?

:-)


Gee, what a mess because I said I recommended a RT of 0.5 s for a recording room...  I know  RT60 is not reliable measurement for a  small room.

But it maybe a starting point , imagine you check the Schoroeder plot and most extraplated RT60 curves assume a value of 0.1 s , won't that be an indication the room is too dead ?


:mrgreen:
Yo Andre,

What's a schoroeder plot?  :D  :D  :D

For a bunch of guys claiming to know one or two things about sound we sure are lousy typists.

A Schroeder plot should have a smooth regression.  The schroederplot of a small room will always show a lot of bumps, meaning you're not seeing a stochastic sound field, AFAIK.
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Postby Eric.Desart » Thu Jul 07, 2005 9:42 am

hi,

i find this a very complicated discussion, which for me causes question marks as well.
for me i will always try to measure rt and i feel frustrated if there remain to many uncertainties.

if one uses rt (note: i used the notion if) than speaking about an rt as an absolute seems senseless since rt is related with volume and shape of the room.

but further is the question: what causes something to feel too dead?
an anechoic room feels dead.
but an elevator were the walls are covered with thin carpet feels as dead as well.
a good non-environment room does not feel dead. (style paul, mark)

as such there is a frequency influence. this corty thing in our ears (which relates to our balance) and psycho acoustics is strongly involved.
i think that once we have a linear absorption and get enough information from the room by reflections, in order to match the visual information with the audible spatial information it does not feel too dead.
being outside: i never heard anybody say it feels dead. it hardly can be deader. (except for bottom of cource)

headphones do not feel dead.
however i believe that you can equalize a spectrum heard via headphones in such a manner that it feels dead too.

just some maybe senseless thoughts.

somebody spoke about earplugs and their effect.
well i do have experience  with this.  i've been in factories were people's brain were so adjusted to the use of earplugs, that even during their break (in much quieter rest rooms) i had to ask them to remove them, allowing to speak at a more moderate level with them.
they hardly were aware using them.
in huge companies one sometimes accompanies people learning to get used to earplugs, a bit comparable with people learning to get used on eye lenses.
put an earplug in only one ear and use it for an hour. lots of people will feel sick. one's coordination gets scrambled.
still there are people one sided deaf living normal lives.

if i did measurements in factories where there is a type of noise where one's brain could not allocate the noise to specific sources, i got exhausted in no time trying to keep concentrated on my work. (e.g. bottle factories)
the same levels and protection in other factories with other types of noise and i could go on for MUCH longer.

summary:
feeling dead is not just a matter of rt.
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Postby bert stoltenborg » Thu Jul 07, 2005 10:56 am

Hey Eric,

Do you have a clue about:

Reproducability of measured RT in small rooms
Reproducability of measured RT in small rooms, measured by different systems?

Is there research done about RT in small rooms?
And about using different systems, like gunshots, MLS, TDS, etc?

Bert
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Postby Scott R. Foster » Thu Jul 07, 2005 10:58 am

being outside: i never heard anybody say it feels dead. it hardly can be deader. (except for bottom of cource)


Excellent point... picture yourself in a marshy green field with no tree cover... not much RT eh?  It takes a sound as loud as a lightening crack to get an echo, and even that seems to come from the horizon [miles away]... but it doesn't sound dead at all.
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Postby andrebrito » Thu Jul 07, 2005 10:59 am

Eric,

You are right about that , that our brain has some sort of impact on what makes you say "this space is a dead room"

You don't have reflections in an open space...  so why does an open space feels so different from a dead room ?

I was thinking that first mankind is used to live outside so it's something that's in our genetics. I mean try to stay a month in a room without going out and you'll probably go crazy ( that explains now how come most metal music comes from nothern european countries like Norway or Sweden!) hahaha

Also outside there's a sence of spaceness visually speaking so I think you pay more attention to your vision then to your ear. There's also some background noise (birds, leaves, and neighbours screaming) there's something which you are used to.

I think that when you enter a room your brain expects to hear some early reflections. Your body pays more attention to hearing in order to locate a sound source in a room.

Now I've been in an anechoic chamber and it was a pure terror... the sense of total silence  for me is what gave me the impression of a dead room and for sure it did scrambled my sense of balance.
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Postby Bob » Thu Jul 07, 2005 11:41 am

I don't know if I'd call it dead, but I've been to many an outdoor concerts in an open field that didn't sound right.
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Postby Zaphod » Thu Jul 07, 2005 12:01 pm

andrebrito wrote:Eric,
There's also some background noise (birds, leaves, and neighbours screaming) there's something which you are used to.


I think this is the point.
Outdoors you'll always have a certain amount of noise surrounding you.
Take this off and you'll feel deadness also outside (it's worth noticing that
dead in this case is more literal than in listening rooms :| ).
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Postby Rod Gervais » Thu Jul 07, 2005 12:42 pm

Gents,

I have to agree that the human mind lives with - and therefor expects - to hear noise - constantly.

When I built the Bongiovi Studios - the small iso boot was so well isolated (it was actually an iso booth within an iso both) - and the air handling system so quiet - that when you walked into the room and stopped to listen - you could almost feel a pressure on your ears pushing out.  As if the ear drum was so un-used to being in a state with no sound pressure pushing in on it - that the reverse was taking place.  Yet when you spoke in the room there was a slight reverb.

I remember that the carpenter foreman brought his wife to see the facility when it was completed - and she freaked out - started actually screaming - within a few seconds of entering that room because of the effect it had on her. She was screaming that she had to get out or she would die. She never had an attack of claustrophobia before in her life - and afterwards she couldn't explain what exactly had happened to her.  But she wouldn't even consider going back into that room.

From the moment of conception we are surrounded by noise- the absence of it is an alien thing to us.........

Sincerely,

Rod
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Postby Eric.Desart » Thu Jul 07, 2005 1:24 pm

zaphod,

i mean with feeling dead, not necessarily silence, but when a source is playing.
if one talks to one another in an anechic room, it feels dead.
if one talks to one another outside it doesn't  feel dead.  now i don't know how it should sound if the backgound are 0 db levels.  :)  i assume one must go to another planet to find those.

a reverb room can be as silent as an anechoic room. still the feel is 10000% different. also when there is no sound.

bert,

there certainly are studies, but i'm more a user than studying systems.
since small rooms are not rare (housing, offices etc) i did lots of them, and tested myself.
mostly i get reasonable statistical accuracy.
i said before that i use custom software written at the kul, to manually control such calculations.
well, for certain data sets we gave them to different persons, to check compatibility, which clearly showed that experience in interpretation played a rol, the more feeling for those curves the better the compatibility between results analysed by different persons.

i also checked lab measurements as per standard procudure versus gun shots in the same lab with very good result.
it is standard a bit seen as worse to use gunshots versus excitation by speakers (filling the room with energy). it's a bit elitary using speakers.
however in the industry we are often confronted with a shortage in s/n.  it's easier to carry guns and mini cannons (i have several types) than speakers and amplifiers.  one can gain with speakers by playing band by band.
but this lenghtens procedures enormously and is at the expense of the number of measurements.
this procedure i discussed with prof vermeir often, and he supported this gunshot method.
any comparison i did, did not show me any limitations with using gunshots.

mls gave the advantage of better s/n, but lower emmission levels.

summary:
i never did real systematic study myself to compare different systems as a goal in itself.
i just used the available accepted equipment and methods and comparisons i made showed we had good statistical and reproducable data.
and by manual controlling critical data, i know which data can't be trusted and will be excluded as decision influencing parameters.
i can define the statistical boundaries for individual measurements/bands to be in- or excluded.

however i expect more systematic investigation to excist.
you also spoke about question marks with fft. well i don't really have the background to judge the systems in itself.


andre

when the labs in leuven univ where build (before my time) and strange stories and assumptions about anechoic rooms still excisted, one payed students (chronical shortage in money) to overnight in those rooms to see what happened.
they were not supposed to sleep, had books to read and light.
well they got used to it. no real exciting story is there i can remember. just that they had more students offering their services than desired (money and adventure attraction -  :mrgreen:  something to impress their girl friends with).
but i agree it feels strange.
but a reverb room does as well certainly without the diffusers (max reverb)
Last edited by Eric.Desart on Thu Jul 07, 2005 2:22 pm, edited 1 time in total.
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Postby Zaphod » Thu Jul 07, 2005 1:57 pm

Eric.Desart wrote:zaphod,

i mean with feeling dead, not necessarily silence, but when a source is playing.
if one talks to one another in an anechic room, it feels dead.
if one talks to one another outside it doesn't  feel dead.  


I understand what you mean.
We are used hearing voices inside and outside, maybe listening to a
speaker sistem could feel dead outside...

Eric.Desart wrote:zaphod,
now i don't know how it should sound if the backgound are 0 db levels.  :)  i assume one must go to another planet to find those.


A dead planet?  :mrgreen:

PS
All this acoustic and home theater stuff has made me aware of something
i had all my life at hand, but never noticed.
I probably have some degree of tinnitus. :|
It's just somewhen in the last year i noticed it as something not-normal  :bang
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