Re: "the objective(s)"
I think we're forgetting one important factor: giving the customer what they want. All this talk about objectives makes it sound like there's only one correct answer. It also suggests that there's a sliding scale, along which some speaker designs are "objectively" superior to others, while forgetting that those so called objectives may be different for different people.
There's the issue of priority: given a set of adjectives to describe a sound system, not everyone will have the same preferences.
I think we're forgetting one important factor: giving the customer what they want. All this talk about objectives makes it sound like there's only one correct answer. It also suggests that there's a sliding scale, along which some speaker designs are "objectively" superior to others, while forgetting that those so called objectives may be different for different people.
There's the issue of priority: given a set of adjectives to describe a sound system, not everyone will have the same preferences.
CeramicMan said:
I think it's a question of basic assumption, of point of departure - objective/intersubjective vs subjective
This discussion concerns a specific problem considered from a perspective of an OBJECTIVE ideal of "high fidelity" / accuracy / realism(objectively defined)
From that perspective what customers want is simply irrelevant.
But can we possibly discuss the problem from a persepctive of individual preferences?
IMHO it would be totally pointless because from this perspective of individual preferences there is simply little if anything to be discussed.
After all "de gustibus est non disputandum"
gedlee said:
perhaps my English is weak but I can assure You that I am not at all biased!
I can see "Mr" and "Mr" here:
>Are we going to find out what Mr Geddes has found?
>Are we going to find out what is in Mr Toole's paper
as well as "Mr" and "dr" and "absolutely nothing at all" here:
>What new and interesting was Mr Geddes going to tell us?
>Why did dr Toole any research in "The Acoustics and
>Do You think that Toole just
perhaps I'm rather biased against Dr Toole as I denied him the capital "D" when writing "dr Toole" (and not "Dr Toole") and even more biased as I denied him even his "Mr" impolitely writing just "Toole"
the truth is that I am neither biased nor rude
it was just a mistake and a misunderstanding for which I apologize
I'm really sorry Dr Geddes!
I am really not biased!
graaf said:
In Lynn's thread, I posted precis for several of the better AES papers on audibility of resonance and reflection.
Within, one study found that the audibility threshold of very low level delayed resonance was made more audible, under limited signal conditions, when room reverberation was present.
Delayed resonance is not reverberation, but as far as hearing mechanism goes, this raises the need to seriously consider that playback reverberation may increase the audibility of a recording's natural acoiustic. This would be easy enough to explicitely test for.
Dave
DDF said:
thank You so much DDF for very valuable input!
I have made a selection of particularly interesting findings:
- Music was always the least revealing of resonances, especially music that contained any natural reverberation in the recording.
- the presence of room reverberation led to easier audibility of delayed resonances when transient sources were used.
from "Modification of Timbre by resonance: Measurement and Perception" by Floyd Toole and Sean Olive, JAES, '88.
- reflections in the same direction as the first incidence can be 5 to 10 dB above the first incidence before detection;
- lateral reflections increase spaciousness when just above the noticeability threshold;
- lateral reflections less than 10 ms lead to image spreading;
- lateral reflections from 10 to 40 ms lead to image spreading and spaciousness;
- reflections have to be 7 dB above the absolute detection threshold before they cause an image shift
from "The detection of Reflections in Typical Rooms", Olive, presented at the 85th AES convention, preprint # 2719 (F-1)
- early reflections up to 600uS cause localization distortion due to image spreading
- 20 to 40 ms reflections increase ambience
from "A psychoacoustically optimized loudspeaker", Kantor, presented at the 77th AES convention, preprint # 2190
- short term reflections at least 10 dB below the first incidence do not create image shift (Olive found the threshold was 7 dB)
from "The effect of Loudspeaker Radiation Patterns on Stereo Imaging and Clarity", Queen, JAES 1978
- again, spaciousness is a lateral phenomena: its increased by decreasing inter-aural correlation.
- to add spaciousness, augment left minus right lateral reflected energy.
- smaller rooms decrease the ability to localize low frequencies, pulling them to the center of the stereo pair.
- room modes at low frequencies alter the phase relationship between pressure and velocity (relative to free field), interfering with the ability to localize.
from "Spaciousness and Localization in Listening rooms and their effects on the recording technique", Griesenger, JAEs Vol 34, No4, 1986
DDF said:
and perhaps Toole did the test in his "The Acoustics and Psychoacoustics of Loudspeakers in Small Rooms" research project and presented the results to the AES
if it is the same mechanism as with delayed resonance that "playback reverberation may increase the audibility of a recording's natural acoiustic" than it perfectly makes sense that it can at the same time improve speech intelligibility as speech is extremally resonant, isn't it?
graaf said:
but I'm totally dissatisfied with the content of this thread so far
Don't be. If you have small music which could fit into a small room, you can play with speaker directivity and diffusion/reflection , just like you would do in a (very) small venue to get good sound.
If you want big music in a small room, create the early reflection and reverb tail pattern of a large room and make sure that it is directionally correct at the listening position. You need additional methods to position the direct sound within the sounfield and you are pretty much set.
DDF said:
Very interesting, Dave! Makes me think of dithering or other noise added to the signal that tends to bring out low level detail - oddly enough.
One way to start listening for it might be to use jl ohl's
The Final Cut software. It would allow simulation of those reflections. Well worth trying.
Graaf: Thanks, lots of good info there. I like Griesenger's work. He tests on different signal types - music, speech, etc. to determine audibility. And all you have to do is fire up a Lexicon reverb to hear that he knows his stuff!
Dr. Geddes: Sorry, I've been calling you "Mr. Earl" as a wink to Harley Earl of General Motors.
Hope you weren't offended. Is it OK if we call you "Doc Gee"?A question for you. What do you consider a "small" room. Do you have a surface area or volume in mind?
For me, under about 60M^2 would be a small room. Above about 200M^2 would be a large room. I've heard a lot of great systems in that in between "medium" size room. What's small for you?
Graaf posted:
what You have described is a "standard approach", absolutely nothing new at all
It's not a standard approach at all.
The standard approach, which is 99.9% of all speaker application, is to throw omni directional speakers in a room and turn them on. Then, because the listening experience is ultimately unsatisfying, to complain.
it was written thousand times here and elsewhere, just everywhere
Even if this were so, what difference does that make if what I wrote is correct?
Think how is it possible that people praise the space-recreation aspects of omnidirectional designs?
(1)They enjoy the euphonic distortion introduced by the small room. I've been there, have the T shirt.
(2)They think, incorrectly, they are getting all the musical information contained in the recording. I've got that T shirt, also. (3)They don't know any better because they haven't heard speakers operated as I described in the summary. I've got that T shirt, as well.
Why did dr Toole any research in "The Acoustics and Psychoacoustics of Loudspeakers in Small Rooms" if everything is so simple and clear?
It was not clear and simple before he and Geddes did their research. I don't think for one minute that Toole believes loud direct early reflections are desirable
and what about Mr Moulton who insists that the smaller rooms are not at all bad but even better?
Have You read the interview with him?
I've read the interview. He says:
we now know that wide dispersion of high frequencies, resulting in a reasonably flat power response laterally, is ideal behavior.
For small rooms, I think he's wrong. He prefers the masking behaviour of flat lateral power response because he gets lots of ambience, he likes this but he gets it at the cost of lost and distorted musical information.
And also:
I have very wide dispersion speakers in a very wet, large room.
He says a LARGE room. We are talking about small rooms: Specifically, the objectives of operating speakers in small rooms.
Moulton then generalizes to a small room but his small rooms are treated to a faretheewell with a dead front wall, strong bass trapping and hf dispersion (not absorption) treatments on the side walls and a live back wall - his rooms are recording studios. His room treatments are not much different from Geddes's prescriptions, nor from the characteristics of Tool's own home living room.
(Speculation: Moulton's "wide dispersion speakers" probably have really interesting narrowing directional and power distribution characteristics at higher frequencies.)
There are two inter-related topics here: one is objectives of using speakers in a small room. The other is characteristics of a small room as used for listening to recorded music.
Since I don't know what the characteristics of any specific room are, I have to stick to the general case, as in my previous post.
You should find this article by Floyd Toole interesting:
http://www.harman.com/wp/pdf/LoudspeakersandRoomsPt2.pdf
particularly pp22 and following.
what You have described is a "standard approach", absolutely nothing new at all
It's not a standard approach at all.
The standard approach, which is 99.9% of all speaker application, is to throw omni directional speakers in a room and turn them on. Then, because the listening experience is ultimately unsatisfying, to complain.
it was written thousand times here and elsewhere, just everywhere
Even if this were so, what difference does that make if what I wrote is correct?
Think how is it possible that people praise the space-recreation aspects of omnidirectional designs?
(1)They enjoy the euphonic distortion introduced by the small room. I've been there, have the T shirt.
(2)They think, incorrectly, they are getting all the musical information contained in the recording. I've got that T shirt, also. (3)They don't know any better because they haven't heard speakers operated as I described in the summary. I've got that T shirt, as well.
Why did dr Toole any research in "The Acoustics and Psychoacoustics of Loudspeakers in Small Rooms" if everything is so simple and clear?
It was not clear and simple before he and Geddes did their research. I don't think for one minute that Toole believes loud direct early reflections are desirable
and what about Mr Moulton who insists that the smaller rooms are not at all bad but even better?
Have You read the interview with him?
I've read the interview. He says:
we now know that wide dispersion of high frequencies, resulting in a reasonably flat power response laterally, is ideal behavior.
For small rooms, I think he's wrong. He prefers the masking behaviour of flat lateral power response because he gets lots of ambience, he likes this but he gets it at the cost of lost and distorted musical information.
And also:
I have very wide dispersion speakers in a very wet, large room.
He says a LARGE room. We are talking about small rooms: Specifically, the objectives of operating speakers in small rooms.
Moulton then generalizes to a small room but his small rooms are treated to a faretheewell with a dead front wall, strong bass trapping and hf dispersion (not absorption) treatments on the side walls and a live back wall - his rooms are recording studios. His room treatments are not much different from Geddes's prescriptions, nor from the characteristics of Tool's own home living room.
(Speculation: Moulton's "wide dispersion speakers" probably have really interesting narrowing directional and power distribution characteristics at higher frequencies.)
There are two inter-related topics here: one is objectives of using speakers in a small room. The other is characteristics of a small room as used for listening to recorded music.
Since I don't know what the characteristics of any specific room are, I have to stick to the general case, as in my previous post.
You should find this article by Floyd Toole interesting:
http://www.harman.com/wp/pdf/LoudspeakersandRoomsPt2.pdf
particularly pp22 and following.
graaf said:
I should clarify... I meant objective/s in the sense of 'goals' - what someone wants to achieve when they build a sound-reproducing system.
From a scientific point of view, there may be no such thing as an "objective" approach for several reasons:
1) Typically, there's insufficient information in the recording to reproduce what the listener may want. For example, simple triangulation of a sound source requires a minimum of 3 strategically positioned microphones - 4 to preserve information in 3 dimensions. In reality though, many microphones are positioned extremely close to the sound source - pressed against a singer's lips or placed a foot away from an instrument. Unfortunately, the sound "engineer/s" often don't seem to know what they're doing and their priority is to eliminate background noise mechanically rather than with intelligent postprocessing.
2) Wild decoupling of the listener from the "listening points". It's pretty obvious that high quality headphones are required to provide the most accurate reproduction of imaging, soundstage information and whatnot. However, I suspect that this point is being avoided because it's a loudspeaker forum and there may be a bit of snobbery involved, friendly rivalry, or like I suggested earlier: different subjective preferences.
As for optimizing the acoustic response of a small room so that the listener is not confined to a sweet spot: active noise cancellation is one option.
Another option could be to control the reverb characteristics in the recording so that the listening room enhances the desired effects. Either way, purist 2-channel stereo ideals fly out the window.
It safe to say Dr. Geddes has a strong idea about what a loudspeaker should do in a small room, and I would love to learn more about how he implements them practically, considering he has more practical experience than a lot of us. People can have different opinions, of course, but hearing from someone with much practical experience is a boon to us all, you know?
Earl, could you set up some 'boundary conditions'? Say you had a new client, with a 15'*20' living room, opening on one end to the rest of the house. Spouse approval not considered... Where would you go from there?
Patrick
Earl, could you set up some 'boundary conditions'? Say you had a new client, with a 15'*20' living room, opening on one end to the rest of the house. Spouse approval not considered...
Where would you go from there?Patrick
I may have a completely different question to Mr Geddes.
I understand pretty much completely your reasoning behind Summa, and it indeed makes a pretty compelling case.
What I haven't seen so far discussed (or mentioned in Summa's papers) is how is box coloration addressed. I have to say here that I have never heard Suma, but I have heard reasonably large number of so called high-end box solutions, many of them universally accepted as well engineered (ATC, B&W, Avalon, Thiel, Vandersteen, Duntech/Dunlavy to name just a few). They all now sound colored to me after hearing boxless speakers (Linkwitz Orion, Gradient etc.). This coloration is combination of box resonance and reflexed sound emanating through the woofer membrane. It is very characteristic, and once you hear it you always hear it (yes, it is a curse).
We all know about waveguide and its magic in Summa, but is there any special trick to adress box colorations as well ?
Because as it stands now, I am inclined to view boxless speakers as preferred in-room solution.
At least until I perhaps get a chance to hear Summas in Melbourne (unlikely as it seems).
Bratislav
I understand pretty much completely your reasoning behind Summa, and it indeed makes a pretty compelling case.
What I haven't seen so far discussed (or mentioned in Summa's papers) is how is box coloration addressed. I have to say here that I have never heard Suma, but I have heard reasonably large number of so called high-end box solutions, many of them universally accepted as well engineered (ATC, B&W, Avalon, Thiel, Vandersteen, Duntech/Dunlavy to name just a few). They all now sound colored to me after hearing boxless speakers (Linkwitz Orion, Gradient etc.). This coloration is combination of box resonance and reflexed sound emanating through the woofer membrane. It is very characteristic, and once you hear it you always hear it (yes, it is a curse).
We all know about waveguide and its magic in Summa, but is there any special trick to adress box colorations as well ?
Because as it stands now, I am inclined to view boxless speakers as preferred in-room solution.
At least until I perhaps get a chance to hear Summas in Melbourne (unlikely as it seems).
Bratislav
jlo said:
Not sure about measurements, but this is a fairly credible source ...
http://www.linkwitzlab.com/frontiers.htm#A
fcserei said:
I think You know the cause of my dissatisfiaction
anyway
Do You think that it is really necessary to "create the early reflection and reverb tail pattern" when we have natural or artificial "reverb tail pattern of a large room" already in the recording of "big music" and we have also "early reflections" already in our listening room?
Perhaps all we need is to remove the room's own reverb (i.e. everything after 50 ms) as Mr Moulton suggests?
What do You think?
CeramicMan said:
no clarification needed
my English is not that bad
I know what You meant and I know what I meant
CeramicMan said:
non sequitur
I can't see any logical connection between the reasons You give and Your statement that "From a scientific point of view, there may be no such thing as an "objective" approach"
On the other hand I think that nobody is going to question that "de gustibus est non disputandum" and it logically follows from that that in any reasonable discussion We have to make objectivistic or at least intersubjectivistic assumptions.
Beacuse we have to have a common point of reference to be able to discuss anything at all. Without that it's only talking past each other. Bla bla bla
In "high fidelity" the reference is the physical reality in front of microphone the fact that "the sound "engineer/s" often don't seem to know what they're doing" notwithstanding
CeramicMan said:
not proven
I think that You are wrong with that "triangulation of a sound source" argument beacuse I think that for recreating a realistic 3D sound picture "triangulation of a sound source" is not at all necessary
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.