is this really a problem with blind tests?

[johncarm]

  evidence of the accuracy of echoic memory, well, does it matter? it's not like long listening bypasses echoic memory, so whatever inaccuracy will at the minimum be ported onto the next step of memorization. there is no memory of sound that we got without the echoic memory step anyway.
evidence that more time leads to more mistakes in recalling audio information, well there is your everyday life experience. else I remember 2 papers on the subject, but finding them again is another story. I have pdfs and bookmarks about audio that are like the treasure cave in ali baba. I know how to open the cave, but then it's just a giant mess of all the stuff I will mostly never read again that I didn't even care to rename properly for the sake of future search ^_^.
but in any way you won't be satisfied by those, as to test short vs longer recall, the test requires to have a short sample in the first place so that it doesn't exceed the echoic step.
 
again what you explain sounds to me like when I would want to analyze music in my head to get a sense of something, a perceived preference or whatever. and that is not the purpose of a blind test!!!  I'm not saying long listening can't have it's use or that we should judge music based only on short samples. let's make this very clear, I'm talking about trying to discriminate 2 audio samples here! nothing else.  now let's say I'm setting up my EQ, to decide if I'll keep it, just turning it ON and OFF a few times is not a good method because my impressions will be impacted by the "louder is better" feeling. instead I'll use that EQ for some times, then turn it off and listen again without any particular timing or agenda. only then will I decide if I preferred one or the other. that's taste.
but if my question was "is this EQ sounding audibly different compared to no EQ?" then of course I would just turn the EQ ON/OFF repeatedly while playing music and see if I detect a change.

 
It's not "the accuracy of echoic memory", it's the accuracy of the comparison in echoic memory. 
 
Second, there's no need to analyze music. I'm simply describing the reality of a musical signal which is that it has repeated similar but slightly different features. 
 
The big questions here are (1) what is our model of aural memory, and (2) how does that inform our choice of test signal.
 
Say we are choosing between a signal that repeats features many times, versus a signal that has only one repetition of each feature. What does your model of aural memory have to say about that? How does the difference between those two kinds of signals affect the way they are remembered, in your model of memory?

 

[spruce music]

I didn't say "differences between A and B", I said the signal resulting from the subtraction of B from A, i.e. "A-B".

Think about it this way. Suppose someone tells you that a listener has a choice of two signals, A and B. They want you to analyze the signals and comment on what the listener might hear in each one, and how they might experience a difference.

Now suppose that the only information you are provided with is the signal "A-B". What would you be able to determine about this listener's experience? What wouldn't you be able to determine?

The answer to that question tells you something about how relevant A-B is.

Yes the answer tells much. The difference signal by itself would also tell much if you know it's source. You don't seem to have understood, but that doesn't make it not so.

 

[johncarm]

Yes the answer tells much. The difference signal by itself would also tell much if you know it's source. You don't seem to have understood, but that doesn't make it not so.

 
Can you give some specifics? If you know only A-B, what theories would be available to you to answer the question about audible differences? 

 

[spruce music]

Can you give some specifics? If you know only A-B, what theories would be available to you to answer the question about audible differences? 

you have to know the relative level of the original vs A minus B. It is very simple if the differences are small enough the ear fails to perceive it. The null level is a numerical representation of how different two things are.

 

[johncarm]

you have to know the relative level of the original vs A minus B. It is very simple if the differences are small enough the ear fails to perceive it. The null level is a numerical representation of how different two things are.

So if I tell you the relative level of (A-B) and A, then you can answer the question "are they audibly different?"--no matter what A and B are, no matter whether they are spread spectrum or narrow spectrum, no matter whether they are similar or very different. All you need to know is the one number? And you can answer that question "yes" or "no" with near certainty?

 

[Joe Bloggs]

If A minus B is so quiet relative to A as to be inaudible, how can B be "very different" from A?

 

[johncarm]

If A minus B is so quiet relative to A as to be inaudible, how can B be "very different" from A?

No one said "A - B is so quiet relative to A as to be inaudble." The question is, given A and B, can you determine whether they are audibly distinct without running any listening tests. 
 
EDIT: in fact, Spruce Music claims he can do this knowing only one number, not the whole signal A and B.

 

[Joe Bloggs]

If A minus B is so quiet relative to A as to be inaudible, how can B be "very different" from A?

No one said "A - B is so quiet relative to A as to be inaudble." The question is, given A and B, can you determine whether they are audibly distinct without running any listening tests. 

EDIT: in fact, Spruce Music claims he can do this knowing only one number, not the whole signal A and B.

I don't know what you think Spruce claims. You might have simply led the discussion on a wild gallop so far from the original point that he couldn't relate to it anymore. For my part I've only ever maintained that A would be indistinguishable from B if the error signal A minus B is so low as to be inaudible when amplified to the same extent as A is amplified for normal listening.

 

[johncarm]

I don't know what you think Spruce claims. You might have simply led the discussion on a wild gallop so far from the original point that he couldn't relate to it anymore. For my part I've only ever maintained that A would be indistinguishable from B if the error signal A minus B is so low as to be inaudible when amplified to the same extent as A is amplified for normal listening.

It's a central, important question. Wild gallop? Come on. The question is, how do we answer the question, "Are A and B different?" What theory do we need, how do we know what tests to run and when we need to run tests, what theories do we invoke about the operation of the ear and brain, etc.
 
It appears that you have given a very partial answer. You have identified a case in which we can conclude that A and B are indistiguishable. So what would you do the other 99% of the time?

 

[Joe Bloggs]

I don't know what you think Spruce claims. You might have simply led the discussion on a wild gallop so far from the original point that he couldn't relate to it anymore. For my part I've only ever maintained that A would be indistinguishable from B if the error signal A minus B is so low as to be inaudible when amplified to the same extent as A is amplified for normal listening.

It's a central, important question. Wild gallop? Come on. The question is, how do we answer the question, "Are A and B different?" What theory do we need, how do we know what tests to run and when we need to run tests, what theories do we invoke about the operation of the ear and brain, etc.

It appears that you have given a very partial answer. You have identified a case in which we can conclude that A and B are indistiguishable. So what would you do the other 99% of the time?

Conduct listening tests? Are we not allowed to do that now?

And the given case is not as rare as you think. Quad demonstrated an inaudible difference signal between the original record and the signal fed through its shiny new loudspeaker amp in 1970. All of the error of redbook CD vs hi-res is quantization noise at -96dB and a bunch of ultrasonics.

 

[johncarm]

Conduct listening tests? Are we not allowed to do that now?

And the given case is not as rare as you think. Quad demonstrated an inaudible difference signal between the original record and the signal fed through its shiny new loudspeaker amp in 1970. All of the error of redbook CD vs hi-res is quantization noise at -96dB and a bunch of ultrasonics.

 
 
My point is to establish the basis for claims made on this forum. Just tell me the general area of theory for any given claim. 
 
Spruce made a rather extraordinary claim
 
You haven't made any extraordinary claims. If I sound pedantic it's not aimed at you.
 
But you have made a claim, which is that if A-B is inaudible, then A is indistinguishable from B. What is the theoretical basis for this? Just give me the name of theory. Or the experimenter. 

 

[Joe Bloggs]

Conduct listening tests? Are we not allowed to do that now?


And the given case is not as rare as you think. Quad demonstrated an inaudible difference signal between the original record and the signal fed through its shiny new loudspeaker amp in 1970. All of the error of redbook CD vs hi-res is quantization noise at -96dB and a bunch of ultrasonics.

My point is to establish the basis for claims made on this forum. Just tell me the general area of theory for any given claim. 

Spruce made a rather extraordinary claim

You haven't made any extraordinary claims. If I sound pedantic it's not aimed at you.

But you have made a claim, which is that if A-B is inaudible, then A is indistinguishable from B. What is the theoretical basis for this? Just give me the name of theory. Or the experimenter. 

Well it's masking theory (based on empirical results of masking experiments) isn't it? Intuitively speaking just imagine looking for a needle lying on a blank white floor vs looking for it in a haystack.

 

[johncarm]

Well it's masking theory (based on empirical results of masking experiments) isn't it? Intuitively speaking just imagine looking for a needle lying on a blank white floor vs looking for it in a haystack.

Okay, I'll see what I can find on the subject of masking theory. 
 
But as far as intuition, aren't objectivists always bashing audiophiles for going with their intuition?
 
I "intuitively" think that rapid switching ABX testing doesn't allow one to hear all the relevant detail, but that is a question that needs to be answered by evidence, not intuition.

 

[spruce music]

I don't know what you think Spruce claims. You might have simply led the discussion on a wild gallop so far from the original point that he couldn't relate to it anymore. For my part I've only ever maintained that A would be indistinguishable from B if the error signal A minus B is so low as to be inaudible when amplified to the same extent as A is amplified for normal listening.

That is all I have claimed too.  If you give me A or B, and then give me A-B I can listen to the former at a normal volume, and then listen to A-B.  If I hear silence, I know these two will sound identical.  In fact, they will sound identical at some point where you still can barely hear A-B at normal volume.  If you hear nothing though you have a 10-20 db margin of error and need not worry about it.
 
Now in most systems at normal volume levels the point where this happens is maybe -80 db.  So if you tell me A-B relative to either of the others is -80 db, then I don't even have to do the listening to A-B or anything else. Somewhere around -60 or -70db is where prior work shows we no longer hear a difference between two sources.  But you will hear those levels in an A-B signal.  The extra margin makes it a surety.
 
There are some simple ways you can listen to this yourself if you just need to experience it.

 

[johncarm]

 
That is all I have claimed too.  If you give me A or B, and then give me A-B I can listen to the former at a normal volume, and then listen to A-B.  If I hear silence, I know these two will sound identical.  In fact, they will sound identical at some point where you still can barely hear A-B at normal volume.  If you hear nothing though you have a 10-20 db margin of error and need not worry about it.
 
Now in most systems at normal volume levels the point where this happens is maybe -80 db.  So if you tell me A-B relative to either of the others is -80 db, then I don't even have to do the listening to A-B or anything else. Somewhere around -60 or -70db is where prior work shows we no longer hear a difference between two sources.  But you will hear those levels in an A-B signal.  The extra margin makes it a surety.
 
There are some simple ways you can listen to this yourself if you just need to experience it.

I made my question very clear. I didn't ask: 
 
"Is there some circumstance in which you can tell from A-B if the difference is inaudible?"
 
I asked:
 
"Given A, B, and A-B, can you tell me if the difference is audible?" and as a bonus question "Can you do it without listening tests?"
 
You probably think I'm being pedantic. But this question is at the heart of our knowledge about audio. And a few special cases won't help.
 
I didn't ask "Are there special cases in which we can make a conclusion?"
 
I'm talking about the general case.
 
So, I'm not asking for a scientific paper, but give me a sense of how you would go about answering that question. How about in the case that we aren't running listening tests.