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Perceptual Effects of Room Reflections

tuga

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When looking for an answer you need not only to open your eyes, but your mind as well. ;)
I prefer blind-testing thank you. To avoid bias and indoctrination.

From chapter 7:

In monophonic tests, (10, including Toole and possibly Olive) listeners reported large differences in both sound quality and spatial quality.
However, in stereo listening most of the differences disappeared in these data that average ratings for all programs.
The two highly rated loudspeakers kept their high sound quality ratings, but the loudspeaker with low spatial ratings in mono became competitive in stereo.
This was a puzzle, because it had been assumed that it was stereo that would reveal the relative merits in terms of imaging and space.


If the Quad was judged subjectively worse in mono both in terms of spatial as well as sound quality but almost identical in stereo then we can conclude that since no one listens at home with a single speaker then perhaps the problem is not the narrow dispersion but something else.

Perhaps people when listening in mono preferred the less flat reponse of the other two speakers because it introduced an euphonic quality since both the Rega and the Kef exhibit the infamous BBC-dip at 2kHz.

Or maybe I am just a herectic infidel that should be set-alight.
 

QMuse

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I prefer blind-testing thank you. To avoid bias and indoctrination.

From chapter 7:

In monophonic tests, (10, including Toole and possibly Olive) listeners reported large differences in both sound quality and spatial quality.
However, in stereo listening most of the differences disappeared in these data that average ratings for all programs.
The two highly rated loudspeakers kept their high sound quality ratings, but the loudspeaker with low spatial ratings in mono became competitive in stereo.
This was a puzzle, because it had been assumed that it was stereo that would reveal the relative merits in terms of imaging and space.


If the Quad was judged subjectively worse in mono both in terms of spatial as well as sound quality but almost identical in stereo then we can conclude that since no one listens at home with a single speaker then perhaps the problem is not the narrow dispersion but something else.

Perhaps people when listening in mono preferred the less flat reponse of the other two speakers because it introduced an euphonic quality since both the Rega and the Kef exhibit the infamous BBC-dip at 2kHz.

Or maybe I am just a herectic infidel that should be set-alight.
As you don't understand or accept there is such thing as spatial quality with mono speaker I'm not sure how you can try to speculate about such things.
 

tuga

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As you don't understand or accept there is such thing as spatial quality with mono speaker I'm not sure how you can try to speculate about such things.
I note that the scriptures are missing a glossary.
 
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March Audio

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As you don't understand or accept there is such thing as spatial quality with mono speaker I'm not sure how you can try to speculate about such things.
This is a good point.

Don't speculate its pointless. Read, digest and read again.
 

tecnogadget

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@tuga I think this reached to the point where the whole forum is aware you disagree with testing speakers in Mono.
There are two ways I could think this could carry on. 1- You and the ones replying to the subject keep going in circles to the end of times. 2- You start your own research as did Mr. Floyd Toole as why speaker qualities should never be analyzed in Mono instead of Stereo
The worst thing that can happen is that you are wrong and learn something new.
The Best thing it could happen is you are right and we all learn something new.
It's a win-win.

My 2 cents (I don't know if I'm right or wrong) are that some folks are trying to explain that listening/subjectively between different speakers in Mono helps assessing it's natural character and some parameters like spatial effect/quality, how they interact with the room by means of reflections, etc.

Nobody is denying at the end of the day listening and enjoying music WILL be in Stereo.

This Mono testing is used because it's been proven that it makes for a much accurate evaluation for the above parameters that otherwise would be masked in Stereo.

Using an analogy, how could you make for a better subjective evaluation of sound music? In a crawled audio show or in a peaceful listening room? It is the same thing as saying you would be much more focused on evaluating in Mono than Stereo, which yields less interference and more focused information for your auditory system/brain to interpret/decode. Afterward, you can correlate/extrapolate the findings to Stereo.

Mono vs Stereo does not only stops at speaker counting since its deeply dependent on the signal that is being played. You can have two speakers playing a stereo recording or a mono recording.
 

tuga

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@tuga I think this reached to the point where the whole forum is aware you disagree with testing speakers in Mono.
That is not correct.
I think that mono has its merits for evaluating tonal balance and other shortcomings (obervational assessment), just not preference (tasting) not stereo imaging and "spaciousness".
 

March Audio

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That is not correct.
I think that mono has its merits for evaluating tonal balance and other shortcomings (obervational assessment), just not preference (tasting) not stereo imaging and "spaciousness".
The research was entirely based on preference and its correlation to objective measurements. The preferences were consistent with intuitively obvious technical objective parameters, ie flat on axis anechoic response and smooth off axis response.

Conclusions of speaker preference based on mono testing were confirmed in stereo. Stereo testing, ie any considerations of stereo image, did not affect people's conclusions about what were the preferred speakers.

As techno gadget has alluded to above, you can either accept this or provide some genuine evidence that contradicts it. Saying you don't beleive it's so doesn't really help.
 

tuga

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Conclusions of speaker preference based on mono testing were confirmed in stereo. Stereo testing, ie any considerations of stereo image, did not affect people's conclusions about what were the preferred speakers.
 

SIY

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Side question:

What about speakers that are specifically designed for stereo? The ones sitting in front of me have angled front baffles (21°) for crosstalk minimization, asymmetric absorption (open cell foam on the outside edge), and will not function properly as mono speakers, but work brilliantly well in stereo mirrored pairs.
 

March Audio

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@tuga I think this reached to the point where the whole forum is aware you disagree with testing speakers in Mono.
There are two ways I could think this could carry on. 1- You and the ones replying to the subject keep going in circles to the end of times. 2- You start your own research as did Mr. Floyd Toole as why speaker qualities should never be analyzed in Mono instead of Stereo
The worst thing that can happen is that you are wrong and learn something new.
The Best thing it could happen is you are right and we all learn something new.
It's a win-win.

My 2 cents (I don't know if I'm right or wrong) are that some folks are trying to explain that listening/subjectively between different speakers in Mono helps assessing it's natural character and some parameters like spatial effect/quality, how they interact with the room by means of reflections, etc.

Nobody is denying at the end of the day listening and enjoying music WILL be in Stereo.

This Mono testing is used because it's been proven that it makes for a much accurate evaluation for the above parameters that otherwise would be masked in Stereo.

Using an analogy, how could you make for a better subjective evaluation of sound music? In a crawled audio show or in a peaceful listening room? It is the same thing as saying you would be much more focused on evaluating in Mono than Stereo, which yields less interference and more focused information for your auditory system/brain to interpret/decode. Afterward, you can correlate/extrapolate the findings to Stereo.

Mono vs Stereo does not only stops at speaker counting since its deeply dependent on the signal that is being played. You can have two speakers playing a stereo recording or a mono recording.
Bang on :)
 

March Audio

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It's been explained a number of times now that accurate assessment in stereo becomes more difficult, hence the variation. Please take this on board.

Regardless, the order of preference remains the same.

Toole has been explicit about this. Stereo tests never changed the order of preference over mono. So you can say you don't beleive it as much as you like but until you show some quality objective evidence that contradicts the conclusion, I will stick with Tooles decades of professional research.

@tecnogadget summed it up very concisely.
 
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tecnogadget

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That is not correct.
I think that mono has its merits for evaluating tonal balance and other shortcomings (obervational assessment), just not preference (tasting) not stereo imaging and "spaciousness".
This folks are evaluating speaker preference in mono and its correlation to objective measurements.

The objetive measurements are conducted with only 1 speaker, they are “Mono”.

They found that changing to stereo evaluation didn’t change results regarding preference.

Maybe stereo imaging and “spaciousness” has lesser effects in preference than flat on axis and smooth off axis response.

Is there a technical/objective way of measuring “imaging” and “spaciousness”?? Those are terms way over used by reviewers and forums.
 

tecnogadget

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Enter the Void...Stereo.

If the same evaluations were made in Stereo they introduce so many new variables that makes it much harder. How much separation between speakers ? Should it be the same between all samples ? To toe-in or not ? To toe-out or not ? How many degrees ? Etc
 

Thomas savage

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I can't believe this is still going on , well maybe I can lol

I don't want to see this being bought up continually ( by the same individual(s) ) all over the forum .

Unless we have something more to go on than " I don't agree " I'd ask you all to close this chapter on 'mono Vs stereo for speaker assesment' , notice how that doesn't relate to the OP.

Cheers
 

tuga

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Enter the Void...Stereo.

If the same evaluations were made in Stereo they introduce so many new variables that makes it much harder. How much separation between speakers ? Should it be the same between all samples ? To toe-in or not ? To toe-out or not ? How many degrees ? Etc
Position the speakers and listener for least room interference below 300Hz forming an equilateral triangle, toe-in for flattest response at the listening spot. Also try manufacturer's positioning and toe-in instructions. Treat wall behind dipoles.
In other words set up for best possible performance.

It is a lot more work than mono, I'll grant you that...
 

tuga

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I can't believe this is still going on , well maybe I can lol

I don't want to see this being bought up continually ( by the same individual(s) ) all over the forum .

Unless we have something more to go on than " I don't agree " I'd ask you all to close this chapter on 'mono Vs stereo for speaker assesment' , notice how that doesn't relate to the OP.

Cheers
This is a snippet of the OP:

“It was in this room [Dr. Toole’s Reference IEC room at National Research Council] that experience was gained in understanding the role of first reflections from the side walls. The drapes were on tracks, permitting them to easily be brought forward toward the listening area so listeners could compare impressions with natural and attenuated lateral reflections (see Figures 4.10a and 8.8). In stereo listening, the effect would be considered by most as being subtle, but to the extent that there was a preference in terms of sound and imaging quality, the votes favored having the side walls left in a reflective state. In mono listening, the voting definitely favored having the side walls reflective."

"See the discussions in Chapter 8, and Figures 8.1 and 8.2, which show that attenuating first reflections seriously compromises the diffusivity of the sound field and the sense of ASW/image broadening. One of the problems with both music and movies is that sounds that in real life occupy substantial space—multiple musicians or crowds of people, for example—end up being delivered through a single loudspeaker—a tiny, highly localizable source. The precision of the localization is the problem. Most of what we hear in movies and television is monophonic, delivered by the center channel, so a certain amount of locally added room sound may be beneficial; this is definitely a case where a personal opinion is permitted."

Except no one listens to a single speaker at home...

Now look at fig.7.14
 

QMuse

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Except no one listens to a single speaker at home...
And again we closed a circle only to re-open it once again. :facepalm:

I believe we already established Toole is speaking about listening to the differences between speakers, not listening to the music.
 
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Are IEMs "dull and lifeless"?

Headphones in general?
I'm wondering about headphones too. I rarely see people say that they are too dead sounding.

Another point is that headphones are used really often in ABX'ing things that are very subtle to hear.
 
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