+1, that's absolutely the right question. But I am thinking...
Mostly I guess we all take mic measurements to as a means of quantifying FR and FR is taken is nearly the only issue. Good research can be done with human hearing evaluation (which is our end-point, eh) but it still needs to be quantitative and structured (not to mention blind).
There are the studies Toole reports on speaker likability but not quite what you are asking about.
What's needed is something like azimuthal localization and how the accuracy and precision changes with speaker and room treatments. Or studies of the possibly mythical effect of side-wall comb filtering on ????.
B.
Mostly I guess we all take mic measurements to as a means of quantifying FR and FR is taken is nearly the only issue. Good research can be done with human hearing evaluation (which is our end-point, eh) but it still needs to be quantitative and structured (not to mention blind).
There are the studies Toole reports on speaker likability but not quite what you are asking about.
What's needed is something like azimuthal localization and how the accuracy and precision changes with speaker and room treatments. Or studies of the possibly mythical effect of side-wall comb filtering on ????.
B.
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What exactly are you looking for? Are you wondering if acoustic treatment actually affects what we hear? Are you wondering if it makes it better/worse?
Acoustic treatment has been around for ages, and covers things so broad it's crazy. You can go all the way back to the work done by Wallace Sabine, who investigated absorption in a Harvard lecture room. His work has been built on and expanded to no end. You can find a lot of published papers on Journal of the Audio Engineering Society or similar audio societies.
Floyd Toole, who bentoronto mentioned, has put out a lot of whitepapers that are highly regarded by the acoustic industry and covers various aspects of psycho-acoustics.
I doubt you'll find a double blind peer reviewed test showing acoustic treatments can be effective, it's kind of accepted as a fact because so many people have experienced and measured it. We can quantify exactly how absorption effects intelligibility thanks to the work on men like Sabine and Toole.
Acoustic treatment has been around for ages, and covers things so broad it's crazy. You can go all the way back to the work done by Wallace Sabine, who investigated absorption in a Harvard lecture room. His work has been built on and expanded to no end. You can find a lot of published papers on Journal of the Audio Engineering Society or similar audio societies.
Floyd Toole, who bentoronto mentioned, has put out a lot of whitepapers that are highly regarded by the acoustic industry and covers various aspects of psycho-acoustics.
I doubt you'll find a double blind peer reviewed test showing acoustic treatments can be effective, it's kind of accepted as a fact because so many people have experienced and measured it. We can quantify exactly how absorption effects intelligibility thanks to the work on men like Sabine and Toole.
A learned post, for sure. Yes, an echo-y lecture hall and a dead concert hall are terrible. And while we don't ask physicists to predict flat tires in cars, car drivers do want to buy good tires. And the issue is often not measurement tools per se, but the relationship of quantitative measurement to human perception.
But OP is still quite right that we ought to see evidence based guidance on some room acoustic matters that matter to audiophiles such as comb filtering, dead-end-live-end, diffraction relative to localization, etc.
B.
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (Audio Engineering Society Presents): Floyd Toole: 8601300165110: Amazon.com: Books
You won't get much better than that. That is pretty much the industry bible and covers the things you're talking about quite a bit. It's been peer reviewed (well, all of his peers use it to teach their classes, which should count). I've got a copy at home, I should read it again, it's been too long.
Yea. I've never really looked, but the only testing that I'm aware of seem to accept it as a given, and are thus investigating narrow aspects of it, rather than trying to "prove" the concept. A friend showed me the work she was doing on this narrow aspect of it, which, as an audio nerd, I thought was interesting: Effects of speech style, room acoustics, and vocal fatigue on vocal effort
The journal it was published in might be another good one to hunt through.
Interesting article. The best room for the task tested has a kind of balanced acoustic environment. Made me think of Toole and ambiance.
How is ambiance measured with tools or even subjectively? How to identify optimum ambiance? Why did the Martin Logan large dipole ESL panels sound so distinctive (and vastly better to my ears) at the HiFi show last week as compared to a lot of point-source boxes?
Pity such a poverty of language to describe hearing perception, in contrast to vision.
B.
How is ambiance measured with tools or even subjectively? How to identify optimum ambiance? Why did the Martin Logan large dipole ESL panels sound so distinctive (and vastly better to my ears) at the HiFi show last week as compared to a lot of point-source boxes?
Pity such a poverty of language to describe hearing perception, in contrast to vision.
B.
We all know that acoustic treatment can make the in room frequency response of speakers more linear.
But what I want to know is if that actually results in a better listening experience. Objective measurements (measure with equipment) only gets you so far, its the subjective measurements (measure with ears only) that really counts.
Thanks!
Ambiance is generally looked at through ETC, RT60, and Spectrograph/Waterfall plots. These tell you how a lot about how it will sound. Cathedrals will have generally high RT60 and an ETC plot with slowly sloping ETC plot, should be no major spikes. Knowing those two things you can kind of begin correlating the two. Just for example. As for the Martin Logan, I'd have to see the room/area they were in to even begin hazarding a guess. Acoustics is also partially subjective, we like different things due to our past and our head/ear shape.
Most room acousticians don't use frequency response, it's not that useful. Sure you'll take a gander at it but there is only so much it can tell you. Part of what Floyd Toole does is correlate the measurements we have to what people like hearing. Sounds like you're wondering more about psychoacoustics than straight room acoustics.
By the way, most people don't like a linear listening experience due to the relative hearing strength we have at different frequencies. We prefer gently downward sloping, -1 dB per octave or so. This has been measured and confirmed multiple times.
What I'm trying to say is, if you know what you the charts are showing you can for sure tell what you're going to hear.
All IMO*: lots of subjective stuff that's about preference cannot be untangled from what a listener is accustomed to hearing / what they like the look of / etc.
That is: somebody who has a small tidy, high $$ system X at home is probably going to like small, tidy systems, and not like the sound of a big, ugly system (even if it has better bass, dynamics etc). Somebody with a $20,000 valve amp at home might decide they hate a system (and skew their listening impressions), because that system uses cheap looking source components. So subjective impressions only matter between people with similar stuff and tastes.
The only subjective thing that trancends this is intelligibility.
e.g. systems A and B appear to have similar measurements. If 9/10 people find that System A remains intelligible against a high noise background, and system B does not, I'd say that system A was subjectively better.
* I'm not a jazz freak / don't listen to many natural recordings, so while I like a drumkit to sound like a drumkit, and a crowd clapping to sound like a crowd clapping, imaging is not really a thing I care about. This skews my opinion on what's important.
Yes.
This sounds very logical, but I would like some proof in the form of blind listening tests. A simple test could be to put listeners in a room where the acoustic treatment/or not is hidden from the listeners with acoustically transparent curtains. Now the listeners don't know what treatment or if any treatment is used. I'm very curious about their listening preferences.
You can simply hide everything from view, then do the test.
I'm imagining right now I have the words best sound reproduction system.
Thanks for all the input guys.
I don't know if that's a tautology, simple-minded wannbee-engineer wishful thinking, or you just don't know how meaningless it is to proclaim that.
B.
In a standard domestic listening room, yes. But my experience in other environments has been different enough to make me wonder if that curve is room dependent. Maybe there are studies on the subject.
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Dr. Floyd Toole:
"Wide dispersion seems to be good, but especially if it is uniform with frequency and the spectra of the reflections is not substantially altered. Hundreds of loudspeakers auditioned by hundreds of listeners in double-blind evaluations have demonstrated this; it is monotonously predictable."
He says in this article that heavy room treatment is helpful for speakers which have bad directivity / uneven off-axis performance.
Room Reflections & Human Adaptation for Small Room Acoustics | Audioholics
Dr Geddes (who also does a lotta blind testing) disagrees with Toole on what to do with early reflections. Toole wants them even, as stated above, whereas Geddes wants them minimised (via high directivity):
YouTube
http://www.gedlee.com/Papers/directivity.pdf
...but they do seem to be in agreement that:
a) less room treatment is needed when the speaker is good.
b) the multi sub thing is > room treatment for smooth LF.
The "proof" of this: neither of these champions of blind testing has much room treatment in their personal listening rooms, and they set up their subs the same way: in multiples, without bass traps.
Revel Owners Thread - Page 321 - AVS Forum | Home Theater Discussions And Reviews
"Four subs [...] No bass traps required"
An Interview with Dr. Earl Geddes of GedLee LLC - Dagogo
"add subs that are as widely spaced about the room as possible [...] Beyond four subs is pretty much a waste of assets"
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Somewhat off topic note:
Some things are difficult or impossible to test blindly. The next best thing is to mask the desired test behind another test.
e.g. 1
http://www.qwantz.com/index.php?comic=458
e.g. 2
I asked a psychologist about "masked" testing (I dunno if there is a better phrease for it), and she said the majority of research in her field is done this way
She did her honours thesis on eating behaviors. Her subjects would answer questions - which was largely a cover task. The data she really wanted was how many of the free cookies they ate when left alone.
e.g. 3
in the study I linked to earlier, the subjects self-reported their level of vocal strain experienced in different acoustic conditions. You could consider that to be the cover task, the underlying data (which, to my reading, looks more significant) being:
"SPL was observed to decrease by 0.86 dB when panels were present"
IMO, if a room effect improves intelligibility (less SPL required to make speech clear) without ruining anything else, then it is a win.
Let's not have any "false equivalence" of authorities just in order to sound balanced.
Toole is certainly the leading name in the field and his book summarizing a mountain of past research is a monument in the field. Moreover, little of Toole's generously supported work in Canada or the US has any taint of commercial misdirection, even when testing Harmon gear.*
B.
*OK, he did say some oddly uncomplimentary things about an ESL with the "anonymous" ID "ML"
Toole is certainly the leading name in the field and his book summarizing a mountain of past research is a monument in the field. Moreover, little of Toole's generously supported work in Canada or the US has any taint of commercial misdirection, even when testing Harmon gear.*
B.
*OK, he did say some oddly uncomplimentary things about an ESL with the "anonymous" ID "ML"
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If I remember correctly, Geddes has his walls set up as panel absorbers (for bass), and uses floor and ceiling treatment.
Not that this has to mean anything other than that they are a good, sensible measure.
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