This from RMAF: "Greatest Technological Breakthrough -
The 'Knowledge Alliance' demonstration performed in the Nordost room, presented by Steve Elford of Vertex AQ and Roy Gregory (former editor of Hi-Fi Plus turned VP Marketing for Nordost) may hold the key to understanding why things like component isolation, power conditioning and cables are important in audio. It may even prove to be a new paradigm in product measurement. By using dynamic material (i.e. real music, and an intriguing 'ting' tone) in place of test tones to measure timing errors from a CD player's output, the team (including deep-geek mil-spec mathematician Gareth Humphrey-Jones) have been able to determine significant improvements in those timing errors when the player is appropriately connected and seated. It's very early days (the roving seminar is more a Call for Comments from the audio industry than anything tangible yet), but it has sent ripples around the high-end community. Maybe there's more to cable measurement than just resistance, capacitance and inductance..."

Think about it. Regards, Norm

I won't waste a brain cell thinking about it until I see some actual papers describing what they're doing and the accompanying measurements. Real science is based on open and transparent peer review.

What I see so far is nothing more than essentially a marketing press release.

Until then, I'll tend to defer to established science and actual professional cabling manufacturers.

This from RMAF: "Greatest Technological Breakthrough -
The 'Knowledge Alliance' demonstration performed in the Nordost room, presented by Steve Elford of Vertex AQ and Roy Gregory (former editor of Hi-Fi Plus turned VP Marketing for Nordost) may hold the key to understanding why things like component isolation, power conditioning and cables are important in audio. It may even prove to be a new paradigm in product measurement. By using dynamic material (i.e. real music, and an intriguing 'ting' tone) in place of test tones to measure timing errors from a CD player's output, the team (including deep-geek mil-spec mathematician Gareth Humphrey-Jones) have been able to determine significant improvements in those timing errors when the player is appropriately connected and seated. It's very early days (the roving seminar is more a Call for Comments from the audio industry than anything tangible yet), but it has sent ripples around the high-end community. Maybe there's more to cable measurement than just resistance, capacitance and inductance..."

Think about it. Regards, Norm

Are the inventors also the folks that stand to benefit most from their invention? Or have they invented a marketing tool to sell expensive, do-nothing cables to the pious audiophiles? Reminds of the tobacco industry's own subsidized studies saying smoking is not harmful. Considering the source, I would also ignore whatever they claim.

I gave up counting the number of "alarm bell" phrases and wording in that release.

The language is similar the deceptive literature used in quack medicines.

Until this "magic" thingy has been submitted to multiple independent peer reviews. Horse manure.

Something tells me that these measurements are similar to MIT's "articulation" measurements. Just a marketing ploy.

once there is an AES paper... then lets talk.

of course, this is just us fools with tin ears talking. to truly learn and grow, we need to expand our thinking.

It appears to be a fairly rigorous test by a well respected third party:

http://www.quantumqrt.com/submenu.asp?MenuID=3&ContentID=26

Still, I'd like to see the same method used to compare the DUT to the DUT repeatedly, to ensure that the results are not random spurious.

1. who is the well respected third party? the company that one of the "team" works for?
2. this is a great case of test gear showing something that may or may not be there.

When i worked for extron, in many cases i would spend seemingly as much time explaining how a piece of test gear worked and what they would see on screen. AND demonstrate the calibration of such, as i did doing the sweeps.

this was to ensure that everybody knew what they were looking at, no switching scale, and clearly labelling all axis of the plot.

those diagrams are a good example of why i took the time to do that.

It is so easy. A levelmatched blindtest is what is needed.

It is so easy. A levelmatched blindtest is what is needed.

Now dont start that again.

THey are claiming instrumentation has found new things that we had not been able to measure. if so, it should be easy enough to interpret and write up.

No need for listening test yet. lets get an explanation first. then we can find ways to challenge the hypothesis.

Now dont start that again.

THey are claiming instrumentation has found new things that we had not been able to measure. if so, it should be easy enough to interpret and write up.

No need for listening test yet. lets get an explanation first. then we can find ways to challenge the hypothesis.

If it's audio, you hear it, or you don't.
A double-blind ABX level-matched listening test is the rubric.
Unless you're judging audio with your eyes? How would that be helpful?
It's not more complicated than that, and it's illogical to suggest otherwise.

If it's audio, you hear it, or you don't.
A double-blind ABX level-matched listening test is the rubric.
Unless you're judging audio with your eyes? How would that be helpful?
It's not more complicated than that, and it's illogical to suggest otherwise.
I hope we all agree that an instrument does a more accurate job than any human in what it measures. It is not like we have people who say they are able to determine things like THD or maximum wattage better than an instrument :).

So if they have found something to measure and that correlates with real hearing tests, that is a novel thing.

Have they come up with a substantive new way of measuring human gullibility?

Some additional info: "...projected a series of graphs that for the first time definitively demonstrated the effects of audiophile power cables, supports, and the Quantum device on sound. They also measured differences between CD players. Simply changing from a stock power cord to a well-made audiophile cord resulted in a 36% reduction in timing errors between the original WAV file and the same file burned on to a CD and played back by a typical high-quality player. Vertex AQ's support platform further reduced noise by 15%."
"Errors and effects that were formerly attributed to jitter have for the first time been identified as program-related using real music as the test signal. These errors cannot be identified by the standard continuous tone tests that everyone and their mother have been using all these years. "We knew this stuff worked, but we didn't know why. Now we can gain insight into how to construct cables, CD players, and amps to produce better sound."
Thoughts? Norm

It is so easy. A levelmatched blindtest is what is needed.

I don't know if the described measurements are BS or not. Likely, they are.

But I find amusing to see that the idea that measurements may show differences between power cords makes a self-proclaimed objectivist suddenly clamor for subjective tests.

If it's audio, you hear it, or you don't.
A double-blind ABX level-matched listening test is the rubric.
Unless you're judging audio with your eyes? How would that be helpful?
It's not more complicated than that, and it's illogical to suggest otherwise.

if somebody claims a new measurement technique, they must prove the MEASUREMENT technique. there has been no discussion yet as to whether they are measuring things that are audible. only that it is a new measurement technique that will prove why you need to buy 30k power cables.

Once the technique is proven or not, then we can talk about whether this technique measures things that are audible. or based on their technique, at what level things are audible. then we can talk about dbt.

by testing, getting results and then correlating them and adding the audibility test we end up with a better measure of hearing and what the element is that we were not currently testing.

provided this is not a load of hooey!:D

when i did the training at extron, we always were showing things that could not be seen, but that we proved were cumulative, so we established the relevance. so we got people to understand why a 2ns rise time for analog video coming out of a 1080P60 source is vital.

i am as firmly fixed on the science side of things as any... but to just yell dbt everytime something is brought out... that is what is illogical.

Some additional info: "...projected a series of graphs that for the first time definitively demonstrated the effects of audiophile power cables, supports, and the Quantum device on sound. They also measured differences between CD players. Simply changing from a stock power cord to a well-made audiophile cord resulted in a 36% reduction in timing errors between the original WAV file and the same file burned on to a CD and played back by a typical high-quality player. Vertex AQ's support platform further reduced noise by 15%."
"Errors and effects that were formerly attributed to jitter have for the first time been identified as program-related using real music as the test signal. These errors cannot be identified by the standard continuous tone tests that everyone and their mother have been using all these years. "We knew this stuff worked, but we didn't know why. Now we can gain insight into how to construct cables, CD players, and amps to produce better sound."
Thoughts? NormDoes this mean the cables were being designed without any insight previously?

We all know that cables, competently designed amplifiers, and DACs sound same to most people. How about a combination of them?

I recently read a subjectivist article on the topic (I don't remember the URL unfortunately). The author was arguing the sound source is degraded at every step starting from music transport until it reaches to our ears. Hence even though an amplifier upgrade may not make an audible difference to the listener, a combination of all those unaudible changes could have been audible as long as there is evidence that signal degradation exists at every step.

To me sounded like an interesting thought and wanted to share

this smells of coming up with a disease to match a cure!

this smells of coming up with a disease to match a cure!

I agree, no matter that it will never sound like what was recorded in the studio,Chamber music recording or at a live Concert recording. Everyone will hear something different even if you are in the studio itself.

Rich Cirincione told me me when he did the sound for Chicago that the Director heard his own unique things and Richard Gere also. They came up with a mix that pleased everyone involved. So even if you are in a good enviroment DB-test mean nothing due to how people hear differently.

I am sure there are a number of modalities that can be tested which can come up with some digital differences between cheap and audiophile products. I am sure some clever 'scientist' could find differences between identical set ups if you tested enough areas..

But do these nuance results translate to subjectively improved sound??? That is the question.

Now dont start that again.

THey are claiming instrumentation has found new things that we had not been able to measure. if so, it should be easy enough to interpret and write up.

No need for listening test yet. lets get an explanation first. then we can find ways to challenge the hypothesis.


Whats the use if one cannot hear it?

if something can be shown in test gear. then an argument can be made that it can be heard. and if it can be shown to be cumulative, then it might show up. and if it can be shown in test gear, then we can use that to determine at what point it MIGHT be audible. so in that case we COULD have a new test that could help to define what sounds good.

At the same time, just because a cable has lower attneuation above 1 meg... it means nothing to audio.

While i am a big fan of DBT, i also recognize that a billion arguments can be made about the testing protocol, etc.

All i am saying is that if they cmail that they can measure the difference between power cords, then lets see the information. then at that point if we have measurements that are explained and repeatable and a new testing methodology, then we can look at ways in which it might be affecting things that we are not hearing. and maybe we are listening to the wrong stuff... i do not know the answers, i just know that in order for science to advance, we have to wlecome all new theories to the table. if those theories stand up, then we apply them to what we know and try to use that to understand new things.

After all, what is the point of string theory? we cant see them!

Oh boy, here we go again...........................................:(

These things never turn out well. We need the "eating popcorn" emoticon here. (i.e., I'll just watch the [predictable] show unfold for entertainment purposes)

i just know that in order for science to advance, we have to wlecome all new theories to the table. if those theories stand up, then we apply them to what we know and try to use that to understand new things.


There is no harm in being skeptical until that theory undergoes peer review, however. This may very well be a legitimate new testing methodology, but given the initial source of the information, I will patiently wait for a less biased review.

what did i say??? i am skeptical and waiting for peer review. i am also saying that in this case, a DBT proves nothing. it is not the panacea to throw up everytime something fishy shows up.

"Simply changing from a stock power cord to a well-made audiophile cord resulted in a 36% reduction in timing errors between the original WAV file and the same file burned on to a CD and played back by a typical high-quality player. "

Interesting but irrelevant w/o more data.

What are the actual errors? I suspect they're already well below audibility, so improvement is meaningless.

"By using dynamic material (i.e. real music, and an intriguing 'ting' tone) in place of test tones "

That is a transfer function, it isn't new.

Shawn

what did i say??? i am skeptical and waiting for peer review. i am also saying that in this case, a DBT proves nothing. it is not the panacea to throw up everytime something fishy shows up.

No, I agree with you completely. I guess I was trying to say that there is a difference between the "wait and see" approach that you are embracing and the naysayers who will dismiss this outright simply because it MIGHT indicate that cables do make a difference, which they don't believe is possible, or because it originated from a biased source.

Sorry if I didn't explain myself more clearly.

There aint' gonna be any peer review, Dizzman.

ah... sorry to jump. it is frustrating sometimes here to be a balanced voiced science fan. some are so quick to jump to things like a DBT where in this case, it is test gear that is being challenged.

ah... sorry to jump. it is frustrating sometimes here to be a balanced voiced science fan. some are so quick to jump to things like a DBT where in this case, it is test gear that is being challenged.

We have test gear that can measure the thermal noise of atoms at almost 0 Kelvin. We can measure electrical properties to the sub-femtoamp range.

There is nothing being challenged here.

No, I agree with you completely. I guess I was trying to say that there is a difference between the "wait and see" approach that you are embracing and the naysayers who will dismiss this outright simply because it MIGHT indicate that cables do make a difference, which they don't believe is possible, or because it originated from a biased source.

Sorry if I didn't explain myself more clearly.
I know Richard Vandersteen is a big believer in the efficacy of different cables as well as other ancillary components. Regards, Norm

We have test gear that can measure the thermal noise of atoms at almost 0 Kelvin. We can measure electrical properties to the sub-femtoamp range.

There is nothing being challenged here.


Cool!:cool:


Nice to know that this sophisticated test equipment is being used on high end cables!:D

;)

Cool!:cool:


Nice to know that this sophisticated test equipment is being used on high end cables!:D

;)

Maybe not in "High-End" audio but it's be used to check transmission lines in "High-End" applications a lot more demanding than any possible HT system.

In the field of signal transmission and processing, high-end audio equipment is still 20-30 years away from current technology used in semiconductor manufacturing tools and testing.

http://china.maxim-ic.com/pdfserv/en/an/AN4303.pdf
http://pdfserv.maxim-ic.com/en/an/AN4338.pdf

Hi

I ghave not posted here for a while but I, also, am taking a wait and see attitude... I have posted some time ago here that Earl Geddes has a different take on things we do take for granted about, for example, how we perceive distortion.. His assertion was/is: Not as well as we think. Under numerous but fairly common conditions, it seems we are not able to perceive 10% of THD very reliably... His papers were submitted to the AES and have not been proved wrong by anyone.. so far.. So I am also waiting for these measurements protocol to come out and be subjected to that kind of peer reviews...

It remains to see how these measurements correlate to perception...

my intention was to say that we have lots of people claiming things that appear to be outside the physical laws of our universe.

and everytime we try to talk about science, we get told "oh, you cant measure the complexity of a music signal" (lets not get into THAT one)

so here we have some folks who are the most snake oily of all the snake oil folks (QRT is beyond description) claiming that they have found a way to measure things in such a way that the efficacy of their snake oil is proven.

So i say bring on the test protocol. let it stand up to scrutiny. however, a DBT is not the answer to this claim. they are claiming a testing methodology, so the only way to prove it is to explain it, and let it show how it works and that it is repeatable.

if from there this can be shown to be used to also detect audible levels of this that or the other thing, then great. bring on the dbt AT THAT POINT.

some of the folks here just yell DBT for anything. and sometimes it is effective and useful (testing to hear an audible difference, testing for preference perhaps even) and sometimes it is not. in this case, it is not

There are good methods to measure already. I have never seen even one audiophile that even once proven something in a DBT that we cannot measure without a problem. That is why I'm sceptic. Why try to find a "new" way of measure if no one can prove the audible difference in a test?

I agree with Dizzman. DBT is irrelevant to their claim at this point. I'm beyond skeptical, but let us see how they try to back up their claim that new measurement techniques prove the worth of the wares.

If for no other reason, sh**'s and giggles.

We have test gear that can measure the thermal noise of atoms at almost 0 Kelvin. We can measure electrical properties to the sub-femtoamp range.

There is nothing being challenged here.
That is not my read of the claim. The claim as I read it was that they could correlate measurements with fidelity improvement in humans. Imagine if there was a new measurement called TFF: Total Fidelity Factor. Imagine there is an instrument which spits out the TFF. You then show through listening tests that there is 1:1 correlation between TFF and improvement users report. Such a thing would be hugely useful and nothing like measuring thermal noise of atoms at 0K.

Of course, it is strange that they have not been forthcoming with the above detail. So likely nothing like this will come about. But the premise is completely different than measuring for measurement sake.

There are good methods to measure already. I have never seen even one audiophile that even once proven something in a DBT that we cannot measure without a problem.
What is your opinion of stereo imaging? That it can be measured or that it cannot be heard in DBT?

That is why I'm sceptic. Why try to find a "new" way of measure if no one can prove the audible difference in a test?
That is a strange argument. If they have indeed found such a thing, you can't argue that they shouldn't have!

I'd be happy to lend one of these.

http://i103.photobucket.com/albums/m129/WBKJ/********MeterDetector.gif

In addition to all the usual warning signs of BS in the text, the thing that sealed the deal for me was this comment by Demian Martin, co-founder of Spectral, in the Stereophile blog report of this presentation (http://blog.stereophile.com/rmaf2009/breakthrough_approach_to_audio_measurement/):


I sat through the presentation. I was struck by the lack of understanding by the presenters of the information presented and the reluctance to offer up any details. I thought the analysis of the data was very lacking and the conclusions presented (cables, noise filters, mechanical isolation make a big difference) were not supported by the by the data presented. This is a big mistake. If there is something in this the initial bad methodology will color the acceptance of it later. The interesting data was in the changes caused by the addition of an accessory, the rest was not particularly meaningful. I'm surprised that the spectrum (FFT of the time data) was not presented. Without the actual data to process its difficult to draw conclusions, especially the "missing link" conclusions presented. The lack of transparency and the vague response to questions about an AES paper or how the measurements were made has this more of a cold fusion story than a breakthrough room temperature superconductor

--Andre

And looks who's the author of that blog. None other than the woo-woo master himself - Jason Serinus.

What is your opinion of stereo imaging? That it can be measured or that it cannot be heard in DBT?


If it can be proven in a DBT it can be measured.

Honestly, those lines read something like...

"We're just now beginning to understand our own products..."

...let alone that I don't buy any of it.

If it can be proven in a DBT it can be measured.
You are asking the same question I asked you! You said everything that we need to measure already has. What is the measurement for stereo imaging?

If it can be proven in a DBT it can be measured.

but just because it can be measured does not mean it can be provenin a DBT.

look there is much we dont know in explaining "good" sound.

as amirm keeps mentioning, how do we measure imaging? we cant.

So let us pretend for a second that these guys have managed to crack the TFF nut and have a way to measure it. and it is measured in %. they say that a TFF of 5% is the lowest threshhold that has been identified in DBT. this means that if a system is measured with 4%, it is inaudible.

When building products, you tie in all sorts of things that are inadible. and hopefully cumulatively they do not add up to be audible.

if a measurement can be put together that gives a measure of total system fidelity... why it strikes me that this could be another weapon in the war against the BS artists.

Not that i think these guys have it.

The Quantum Resonant technology purports non-subtle advantages and improvements to video as well as audio. Surly this should be much easier to quantify, verify and demonstrate in the video realm. Just post an A/B image, if it’s non-subtle, it should easily manifest as such and be easily reproduced and measured. They don’t do a simple A/B image. If the claim is bogus for video, then it makes the audio claim even more suspect and doubtful.

Dave


…Their impact is neither subtle nor hard to hear (or see)…

…QRT’s proprietary circuitry acts at the source of the problem, reducing EMF noise and RFI interference effects on the mains waveform, audio and video signals –…

…Use a QRT purifier and you’ll experience a lower noise floor, greater clarity and separation and increased dynamic range, qualities that are just as apparent (and measurable) when it comes to the color, definition and detail on your AV display…

QRT has already been much lambasted around here. by both the usual characters and a nuclear physicist.

so they are not exactly held in the highest regard.

"as amirm keeps mentioning, how do we measure imaging? we cant."

So you think two speakers that image differently will measure exactly the same?

We can measure the things that contribute to stereo imaging ( power response, channel matching (both in FR and phase), FR, early reflections...etc...etc).

What is far more difficult is correlating the measurements to the subjective impression of the resulting imaging. What one might hear as having great 'depth' another may hear as having a recessed midrange.

Shawn

"What is your opinion of stereo imaging? That it can be measured or that it cannot be heard in DBT?"

"If it can be proven in a DBT it can be measured."

Semantics perhaps, but I don't think it's measurement.

DBT may repeatably demonstrate a subjective perception, but any numbers are tally's to determine statistical significance, not measurements of defined physical parameters.

his point (if i may be so bold) is that at present, we have no way of quantifying many things about sound reproduction. just like in a car we have no way of measuring Fahrvergnügen.

So lets imagine that this is a way to capture that (since we are talking pie in the sky anyways) the folks who believe in an experience namy of the esoteric far out tweaks swear by them. so those of us on the other side of the wire can just keep assuming they are sharing a mass delusion. OR we can assume that they are falling prey to groupthink and biases AT THE SAME TIME keeping our minds open to new possibilities. so while we knowplenty about the signal, why is it so hard to keep open the possibility that a measurement technique that may give some measure of overall playback quality might someday be developed.

not that this is it...

his point (if i may be so bold) is that at present, we have no way of quantifying many things about sound reproduction. just like in a car we have no way of measuring Fahrvergnügen.

So lets imagine that this is a way to capture that (since we are talking pie in the sky anyways) the folks who believe in an experience namy of the esoteric far out tweaks swear by them. so those of us on the other side of the wire can just keep assuming they are sharing a mass delusion. OR we can assume that they are falling prey to groupthink and biases AT THE SAME TIME keeping our minds open to new possibilities. so while we knowplenty about the signal, why is it so hard to keep open the possibility that a measurement technique that may give some measure of overall playback quality might someday be developed.

not that this is it...
Increadibly profound. Norm

Have they come up with a substantive new way of measuring human gullibility?

It is called an invoice.

as amirm keeps mentioning, how do we measure imaging? we cant.


Do you have any proof of this?
As it have been said before, if you can hear it it can be measured. Until one audiophile prove it in a DBT that we cannot measure the change, it is no debate. But that don't mean that we have a "imaging" measuring tool that only measure the "imaging", but that we can measure the difference.

if you can hear it it can be measured.
Yes, but the subsquent measure of human perception is truly standing on rather mushy turf.

Do you have any proof of this?
Yes, I have proof. A search of a metric for stereo imaging shows nothing. I have not read one audio review that has that figure either. And my Audio Percision analyzer has no mention of any test remotely close to it either.

You said anything like this can be measured. So it is you job to show the measure, not mine anyway :).

As it have been said before, if you can hear it it can be measured.
You said it but it was a totally inaccurate statement to make. If we knew precisely how the ear worked, we would be way ahead of where we are. When we were developing our audio signal processing algorithms at Microsoft, despite having a team of researchers with PhD's and such, we still had an army of human testers. If we could measure what they could hear, we would not need any of them! Ditto for all the listening tests MPEG conducts despite having the entire world population of researchers designing their standards.

Until one audiophile prove it in a DBT that we cannot measure the change, it is no debate. But that don't mean that we have a "imaging" measuring tool that only measure the "imaging", but that we can measure the difference.
I am not sure what you just said. But as was noted, DBT is not a precise thing. So there is no 1-1 relationship between it and any measurement. We can talk about correlation but that is it.

Really, your theses makes an assumption that if it were true, would mean an entirely different world than the one we live in. We simply cannot measure everything we hear. And what we measure, we don't always understand. Is jitter of 5 ns at 500 Hz is better, worse or the same as 10 ns at 600 Hz? What if the spectrum of the former is different than the latter? What if we have two components to jitter? Three? How do we quantify the infinite possibilities? DBT? Good luck. My grandchildren will be dead by the time you perform a fraction of that test! :D

There are approximations to be sure but let's not make black and white statements like you did and pretend there is science to back it because there is not.

You said anything like this can be measured. So it is you job to show the measure, not mine anyway.

Once you demonstrate (and we all know what that means) that different electronic units image differently, then measuring this difference will be easy.

I have looked through many test equipment catalogs never saw a meter that measured imaging, but then I never saw a meter that measures what some reviewers call pace either.

ah... sorry to jump. it is frustrating sometimes here to be a balanced voiced science fan. some are so quick to jump to things like a DBT where in this case, it is test gear that is being challenged.

I'm afraid I have to concur with Nin on this one Dizz, insofar as it's nothing new for instruments to measure far beyond the range of human audibility. Therefore, even if we accept this load of bull crap (and I don't accept anything from a company such as nordost absent peer review), it's still meaningless unless the things they are measuring can be proven to be audible in double blind tests.

....
... I have posted some time ago here that Earl Geddes has a different take on things we do take for granted about, for example, how we perceive distortion.. His assertion was/is: Not as well as we think. Under numerous but fairly common conditions, it seems we are not able to perceive 10% of THD very reliably... His papers were submitted to the AES and have not been proved wrong by anyone.. so far.. So I am also waiting for these measurements protocol to come out and be subjected to that kind of peer reviews...

It remains to see how these measurements correlate to perception...

Well, I have a qualm with that since a number of folks have demonstrated the ability to detect THD reliably. His 10% is true for the low frequency band, subwoofer but hardly for the higher bands.
Just a couple of examples from may out there:

http://www.mastersonaudio.com/features/20040401.htm

http://www.axiomaudio.com/distortion.html#

We have test gear that can measure the thermal noise of atoms at almost 0 Kelvin. We can measure electrical properties to the sub-femtoamp range.

There is nothing being challenged here.

Ones imaginations? ;):D

You are asking the same question I asked you! You said everything that we need to measure already has. What is the measurement for stereo imaging?

It would be an irrelevant measurement. You relocate the speakers and imaging changes, no? Yet, the signal from the source has not.
But, some experiments can be done to show how imaging changes, no? Firstly, you need two signal channels at the minimum, right?
Then, you start alerting phase shift of signals to each channel and see what happens. Oh, imaging changes perhaps? How about signal levels? Does the imaging change? Timing of signals? A combination?
Oh, then, who are the listeners? Perhaps the brain's interpretation of those signals are different?
So, in the end, such a complex combination of measurement is irrelevant as any change in the above mentioned info will alter the final image.

There are differences that can be measured, but can not be heard, correct? Thus, trying to measure those differences with a DBT would be a moot point.

The more important question in my opinion is whether serious listeners should really be concerned about inaudible differences.

Reminds me the 120Hz vs. 240Hz debate in LCD displays. 240Hz is measurably superior, but not visibly. Thus, the specification becomes a marketing tool. Nothing more. May not be the ideal analogy, but you get the point.

I'm afraid I have to concur with Nin on this one Dizz, insofar as it's nothing new for instruments to measure far beyond the range of human audibility. Therefore, even if we accept this load of bull crap (and I don't accept anything from a company such as nordost absent peer review), it's still meaningless unless the things they are measuring can be proven to be audible in double blind tests.

Not everyone hears the same way. What one person may hear, you or I may not. Bottom line with any audio gear, if it doesn't sound good or make a difference to you, then don't spend your money on it. I on the other hand had an opportunity to listen to WireWorld's Platinum Eclipse XLRs when before they were released. Needless to say I didn't want to like them because of the $$$$. At the end of the day I tried going back to the Gold Eclipse and it didn't sound the same to me. Lesson learned- never audition something you are not prepared to buy.

As to the thoughts that if someone is making money from it... it surely must be a snake oil... well if you found a unique way to make a product better, why not make money from your efforts? I can't work for free as I'm sure most us can not. So I look forward to seeing some real data like most of us. Until then it's just interesting reading.

Ones imaginations? ;):D

I can imagine being taken.
http://upload.wikimedia.org/wikipedia/commons/4/49/Hieronymus_Bosch_051.jpg

I'm afraid I have to concur with Nin on this one Dizz, insofar as it's nothing new for instruments to measure far beyond the range of human audibility. Therefore, even if we accept this load of bull crap (and I don't accept anything from a company such as nordost absent peer review), it's still meaningless unless the things they are measuring can be proven to be audible in double blind tests.

Not everyone hears the same way. What one person may hear, you or I may not.
Did I say somewhere that all people here the same?

Bottom line with any audio gear, if it doesn't sound good or make a difference to you, then don't spend your money on it.
I won't, thanks. And you're welcome to buy a pound of manure for $1,000,000 if it makes you happy. But what does the have to do with the subject at hand?

As to the thoughts that if someone is making money from it... it surely must be a snake oil...
Who said that if someone is making money on it, it must be snake oil?

I can't work for free as I'm sure most us can not.
Who suggested people should work for free?

You're entire post is nothing but one long strawman argument consisting of responses to statements that were never made. This type of logic is not atypical of many audiophiles.

It would be an irrelevant measurement. You relocate the speakers and imaging changes, no? Yet, the signal from the source has not.
Imaging can be lost or changed at different parts of the chain. It is true that the most dramatic is at the speaker/room. But there are other spots.

Take this example. An audio codec can have what would be called adaptive joint stereo. When the codec is not pressed for bitrate, it would encode both channels in stereo so imaging would match the source (putting aside other distortion). But as bandwidth becomes more limited, the codec then encodes the high frequencies in mono. And the more it starves for bits, the lower the frequency threshold. Such a thing would be clearly audible as the stereo soundstage collapses and expands much like adaptive multi-path filtering for FM radio.

In the above example, the loss of imaging occurs before the speakers so it could be readily measured without them. But paradoxically, you could not come up with any value for it even if you could measure it because it would be highly signal and bandwidth dependent! You could graph it for a specific song and specific data rate but not for all content.

Since it is easy to hear the above effect, yet difficult to measure it, we now have a clear example of the two not going hand in hand.

So, in the end, such a complex combination of measurement is irrelevant as any change in the above mentioned info will alter the final image.
Indeed. Hence the reason I picked this when Nin made his claim :). So many things contribute to imaging loss. But wouldn't it be nice to start to quantify it at least part of the way there?

Did I say somewhere that all people here the same?
Well yes you did when you made a blanket statement "beyond the range of human audibility". I may be able to hear frequencies that you can't and vice versa. On top of that our brains respond differently to audible stimulation. Our nervous systems are very different as well.

The other statements I made were a catchall to previous posts in this thread, and not statements you had made. Instead of posting multiple times I combined them into one.

Well yes you did when you made a blanket statement "beyond the range of human audibility".
Not only did you not quote the full statement, you don't understand what it means. I said "instruments measure far beyond the range of human audibility".
I may be able to hear frequencies that you can't and vice versa.
And you think that contradicts stating that instruments measure far beyond the range of human audibility? Let's suppose I stated that a forklift can lift far beyond the weight that a human can. Would you respond by stating "not everyone has the same strength. What one person can lift, another may not".

And before another strawman argument is forthcoming, my statement in no way contradicts some of the points Amir is making.

Well yes you did when you made a blanket statement "beyond the range of human audibility". I may be able to hear frequencies that you can't and vice versa. On top of that our brains respond differently to audible stimulation. Our nervous systems are very different as well.



When I look at the color red is it the same color you see ? Are you seeing blue and we all call it red ?


Art

all i am saying is that while we can measure the accuracy to many points, it does not always explain why two speakers sound different.

while we can measure the accuracy of a waveform... it is likely that there are other elements to still be interpreted at the listening position.

This from RMAF: "Greatest Technological Breakthrough -
The 'Knowledge Alliance' demonstration performed in the Nordost room, presented by Steve Elford of Vertex AQ and Roy Gregory (former editor of Hi-Fi Plus turned VP Marketing for Nordost) may hold the key to understanding why things like component isolation, power conditioning and cables are important in audio. It may even prove to be a new paradigm in product measurement. By using dynamic material (i.e. real music, and an intriguing 'ting' tone) in place of test tones to measure timing errors from a CD player's output, the team (including deep-geek mil-spec mathematician Gareth Humphrey-Jones) have been able to determine significant improvements in those timing errors when the player is appropriately connected and seated. It's very early days (the roving seminar is more a Call for Comments from the audio industry than anything tangible yet), but it has sent ripples around the high-end community. Maybe there's more to cable measurement than just resistance, capacitance and inductance..."

Think about it. Regards, Norm

One day I was walking down the street talking to a friend who worked on RF receivers with better than -100 dBm sensitivity, which is one 10 trillionth of one Watt.

I exclaimed "That's tiny" at which point a midget went by on a skate board. The little person was not amused, making faces and gestures.

While small amounts of energy upset midgets on skate boards, as long as they can't be perceived in double blind tests where the placebo effect can't happen they aren't relevant to people listening to stereos.

Cable companies are in the business of selling products that are nearly pure profit.

Think about it. Regards, Drew

One day I was walking down the street talking to a friend who worked on RF receivers with better than -100 dBm sensitivity, which is one 10 trillionth of one Watt.

I exclaimed "That's tiny" at which point a midget went by on a skate board. The little person was not amused, making faces and gestures.

While small amounts of energy upset midgets on skate boards, as long as they can't be perceived in double blind tests where the placebo effect can't happen they aren't relevant to people listening to stereos.

Cable companies are in the business of selling products that are nearly pure profit.

Think about it. Regards, Drew

I guess that your not in the Cable Television industry, other wise you would know the day-day cost of operations...?

I guess that your not in the Cable Television industry, other wise you would know the day-day cost of operations...?
I don't think he meant Cable TV companies but people who make A/V cables.

I don't think he meant Cable TV companies but people who make A/V cables.

Sorry, I apologize you are right Amirm.

measurement is not the issue. correlation to what we hear still can use some work.

Yes, I have proof.


I have not seen any proof.

Well, I have a qualm with that since a number of folks have demonstrated the ability to detect THD reliably. His 10% is true for the low frequency band, subwoofer but hardly for the higher bands.
Just a couple of examples from may out there:

http://www.mastersonaudio.com/features/20040401.htm

http://www.axiomaudio.com/distortion.html#

THD is well-known to be a poor measure of error, because it is trying to represent the entire hearing spectrum in one number. Some kinds of 10% THD are trivial to hear, while other kinds of 10% THD are impossible to hear.

--Andre

I have not seen any proof.

burden of proof falls on you. Show us how you measure it. Lack of something can not be proven.

Yes, I have proof. A search of a metric for stereo imaging shows nothing. I have not read one audio review that has that figure either. And my Audio Percision analyzer has no mention of any test remotely close to it either.



A quick search within the AES library reveals a number of papers that discuss measuring stereo imaging. For example, the following 1989 paper; A Computer Model of Binaural Localization for Stereo-Imaging Measurement (http://www.aes.org/e-lib/browse.cfm?elib=5828)

With part of the conclusion that reads:

The results of the experiments detailed in the previous two sections have shown that the present binaural localization model is of use in measuring stereo imaging. Although exact correspondence between the judgements made by the computer model and those of human listeners should be confirmed by formal listening tests, the results are at least qualitatively those that are expected.


It would seem that measuring stereo imaging is not a particularly challenging tasks, those precise co-relation to what we actually hear might be a different matter, but thats true of pretty much everything measurable in Audio anyway :)

THD is well-known to be a poor measure of error, because it is trying to represent the entire hearing spectrum in one number. Some kinds of 10% THD are trivial to hear, while other kinds of 10% THD are impossible to hear.

--Andre

Thanks Andre. It also bears to remind people that THD is the TOTAL Harmonic Distortion exhibited by a given component.Two components can exhibit the same THD and sound vastly different.. since that single number does not give a clue of the relative contribution of the harmonics.
On the subject at hand .. I must say that my doubts are mounting. This too much looks like a pushback because the pressure is building against these stratospheric-priced cables.. They may have felt the need to come up with an objective take on the cable issue.. That has been Nordost slant for a while...

It would seem that measuring stereo imaging is not a particularly challenging tasks, those precise co-relation to what we actually hear might be a different matter, but thats true of pretty much everything measurable in Audio anyway :)

I would put forward that while localizations tests are easy to duplicate. "measuring" a full spectrum soundstage is much harder if at all possible.

As an example. (and please keep in mind that i am completely firmly planted on the science side of things) if i listen to a sound system, i love the big wide image that gets projected... however i have also listened to a system (Ob's as it happens) that had such precise localizations and imaging i was blown away. i mean the voice box on the guitar, the singers voice, etc. it was far beyond a simple stereo localization. i would have sworn i was listening to a left/center/right recording. but it was stereo recording and stereo playback. But it was better than a surround sound recording (at least in front of me.)

So the only point here (and can we please try to not get bogged down in the tiniest little details) is that while we have lots of tools in the arena of measuring accuract of reproduction, we seem to have very little in INTERPRETIVE tools that MAY relate to the quality of that sound being presented. and while much of sound is indeed the beholder, there are perhaps areas yet to be defined that could set a common benchmark.

Saying that "WE KNOW ALL THERE IS TO KNOW AND THERE IS NOTHING LEFT TO KNOW" seems to me to be a little ridiculous. if that was the case, then speaker design would just be a pc program and you could get 90% accurate speakers every single time. and room setup would be a series of tones and you would just shift the speakers per the recomendations from the program.

As we all know, much of this is still trial and error. and balancing different tradeoffs(weaknesses)

While we can measure most of the attributes to many many decimal points, we still do not have completely clear interpretation that correlates to all aspects of how we hear that sound.

And to be totally clear... i do not think for a second that this QRT thing is it. HOWEVER, should they create a protocol and then submit it to the AES and it is accepted, then we could look at it.

BTW, who the phuck is deep-geek mil-spec mathematician Gareth Humphrey-Jones?

BTW, who the phuck is deep-geek mil-spec mathematician Gareth Humphrey-Jones?

Chu, I like your hockey language "phuck". Very creative!!!

Sometimes, it's the only word to use Steve :D

he is a guy who works for the comapny. obviously that was intended to impress the phuck out of us!

And i dont know about you, but i am... never mind. that one would have gotten deleted :D

Yes, I have proof. A search of a metric for stereo imaging shows nothing. I have not read one audio review that has that figure either. And my Audio Percision analyzer has no mention of any test remotely close to it either.

You said anything like this can be measured. So it is you job to show the measure, not mine anyway :).

Amir, this is a complete straw-argument and you know it. What goes into imaging is very complex, and the number of measurements you'd need to take to characterize this perception is huge. There will never be any measurement of imaging because what constitutes good imaging is many things. It isn't a single variable, and any metric that includes all the variables that contribute to imaging would be a very subjective composite of many different measurement variables.

Saying that because there is no measurement of "imaging" that we can't measure everything audible is a totally fallacious argument. It is like saying that there is no measurement of "performance" of a computer. The number of variables that go into computing performance is large, and that characterization would vary heavily depending on what you're doing with the particular computer. So to do a google search and come up with no measurement that captures a computer's entire performance and then claim that we can't measure everything about a computer is totally ridiculous.


You said it but it was a totally inaccurate statement to make. If we knew precisely how the ear worked, we would be way ahead of where we are. When we were developing our audio signal processing algorithms at Microsoft, despite having a team of researchers with PhD's and such, we still had an army of human testers. If we could measure what they could hear, we would not need any of them! Ditto for all the listening tests MPEG conducts despite having the entire world population of researchers designing their standards.

This is because hearing is fundamentally perception and thus can never be measured directly, just like vision. But we can measure the physical stimuli extremely well, just as we can with light as it relates to vision. The secondary part in terms of the subjective impression of that physical stimuli is more complex, but again it isn't possible to measure directly what is occurring in the brain. But if your argument is that there are differences in physical stimuli that exceed our ability to measure but that we clearly can hear, there is nothing to support that contention.

This does not mean that imaging is somehow impossible to study and measure and impossible to discuss what aspects of a loudspeaker contribute to better imaging. Floyd Toole did that precise work, and the results are intriguing. These kinds of listening tests and measurements can be conducted, and they have been. But simply saying that because there is not singular "imaging" metric and that hence imaging cannot be measured or understood objectively at least as far as the physical stimulus is a very manipulative argument.

THD is well-known to be a poor measure of error, because it is trying to represent the entire hearing spectrum in one number. Some kinds of 10% THD are trivial to hear, while other kinds of 10% THD are impossible to hear.

--Andre

While that is true, try that when components are speced at the 3rd decimal digits or there abouts. So, if a component specs around 1%, most likely that may be detected at some parts of the band and not in others, like the low frequencies.

Amir, this is a complete straw-argument and you know it. What goes into imaging is very complex, and the number of measurements you'd need to take to characterize this perception is huge.
Exactly what I said :). See the example I gave on joint stereo in the follow on test.

Let's remember what the argument was. NIN claimed that anything that can be heard in DBT can be measured. I asked him if we could measure stereo imaging. If the answer is "no, it is too complex" then does it mean that we can't hear in DBT? I think not. We hear many things which we cannot measure.

There will never be any measurement of imaging because what constitutes good imaging is many things. It isn't a single variable, and any metric that includes all the variables that contribute to imaging would be a very subjective composite of many different measurement variables.
No disagreement.

Saying that because there is no measurement of "imaging" that we can't measure everything audible is a totally fallacious argument. It is like saying that there is no measurement of "performance" of a computer. The number of variables that go into computing performance is large, and that characterization would vary heavily depending on what you're doing with the particular computer.
Actually, computer performance characterization is much, much easier than the perception problem. In general, computers suffer from three types of resource starvation:

1. CPU

2. I/O (usually disk and network)

3. Memory

Using the right tools we can identify which one is the main cause. Yes, there are composite situations which are harder but having done performance optimizations and thought classes on the same subject at UCSC for more than a decade, the typical cases are very easy to diagnose. I have been in audio for three times as long but yet, have nothing that remotely comes to the same level of measurement for audio.

So to do a google search and come up with no measurement that captures a computer's entire performance and then claim that we can't measure everything about a computer is totally ridiculous.
Let's be clear that I did not place such a boundary on the answer. That is, I did not demand a single number, only whether we can or cannot measure this effect.

But simply saying that because there is not singular "imaging" metric and that hence imaging cannot be measured or understood objectively at least as far as the physical stimulus is a very manipulative argument.
Again, I did not ask for a "single" metric. I asked for any metric in use today. There is none because of some of the reasons you mentioned. It is a complex problem and one that can be dynamic in nature. Further, its effect can be listener dependent.

Really, this was not meant be a deep dive on stereo imaging measurement. But rather to show that life is not so easy where anything you can hear, you can go to a lab and measure. As I mentioned, and Dizz expanded, the world of audio design would be a hell of a lot easier if it were so. But sadly, it is not.

Did I miss something. I thought stereo imaging had a lot to do with a speakers interaction with the room such that if you wanted to you could take a speaker that images like hell, and then just kill it by some precise room treatments. Minor adjustments in position can affect image. A set of measurements would only perhaps give you an idea of how a speaker might image in some rooms with some optimal positioning or am I missing the point?

Exactly what I said :). See the example I gave on joint stereo in the follow on test.

Let's remember what the argument was. NIN claimed that anything that can be heard in DBT can be measured. I asked him if we could measure stereo imaging. If the answer is "no, it is too complex" then does it mean that we can't hear in DBT? I think not. We hear many things which we cannot measure.


No disagreement.


Actually, computer performance characterization is much, much easier than the perception problem. In general, computers suffer from three types of resource starvation:

1. CPU

2. I/O (usually disk and network)

3. Memory

Using the right tools we can identify which one is the main cause. Yes, there are composite situations which are harder but having done performance optimizations and thought classes on the same subject at UCSC for more than a decade, the typical cases are very easy to diagnose. I have been in audio for three times as long but yet, have nothing that remotely comes to the same level of measurement for audio.


Let's be clear that I did not place such a boundary on the answer. That is, I did not demand a single number, only whether we can or cannot measure this effect.


Again, I did not ask for a "single" metric. I asked for any metric in use today. There is none because of some of the reasons you mentioned. It is a complex problem and one that can be dynamic in nature. Further, its effect can be listener dependent.

Really, this was not meant be a deep dive on stereo imaging measurement. But rather to show that life is not so easy where anything you can hear, you can go to a lab and measure. As I mentioned, and Dizz expanded, the world of audio design would be a hell of a lot easier if it were so. But sadly, it is not.

But Amir you are confusing the difficulties here. The difficulty is NOT in measuring the speaker, but in characterizing our perceptions of the speaker. The speaker can be measured. What we don't know exactly is how those measurements correlate to our perceptions of imaging/localization because it becomes much more difficult to perform a large battery of tests on many people to understand just what aspects of the speaker measurements and room effects have the largest impacts on stereo imaging and how that relates to the percieved quality of the speaker.

So you're still wrong in saying that somehow stereo imaging can't be measured. It absolutely can be from the speaker. The complexity is in relating those measurements to our perceptions.

NIN isn't wrong in saying that if it can be heard in a DBT it can be measured. Differences in speaker imaging can be captured in thorough measurements of the speaker. What isn't complete, however, is a thorough understanding of our subjective preferences and perceptions of different kinds of stereo imaging. But you are misusing that to then say that the speaker's impacts cannot be captured and that's fallacious.

That is, I did not demand a single number, only whether we can or cannot measure this effect.

And the answer is YES, it can be measured. It has been measured and studied, just not enough. Again, I direct you to Floyd Toole's book, he has an entire chapter dealing with tests and studies of stereo imaging, and the impacts of dispersion and room reflections, etc and how that affects subjective quality preferences of loudspeakers.

But rather to show that life is not so easy where anything you can hear, you can go to a lab and measure.

Again, you are being very misleading here. You CAN go to the lab and measure. That isn't the challenging part (well, it is expensive to do the kinds of complete on and off-axis measurements we're talking about). The challenging part is to do a battery of listening tests to understand the human perception of these measurements to track down what contributes to stereo imaging preferences.

In other words, the difficulty isn't in measuring the speakers. The difficulty is in measuring the human response to identify what in the speaker measurements contributes (and how) to perceptions of imaging. You are confusing that with some difficulty in capturing what matters at the speaker, and then using that to claim that somehow imaging can't be measured when that simply is not true.

There are good methods to measure already. I have never seen even one audiophile that even once proven something in a DBT that we cannot measure without a problem.Seems like this could be taken a couple of different ways and Amir is taking it one way which might be what was meant, but something else could have been meant.

For instance, did you mean that if somebody can pass a test that 2 things are different we are then capable of doing measurements that show that the 2 things are actually different, or that we can do measurements that 2 things are different and characterize what that means to how people will perceive them (which seems to be the way that Amir took it)?

--Darin

So you're still wrong in saying that somehow stereo imaging can't be measured. It absolutely can be from the speaker. The complexity is in relating those measurements to our perceptions.

The topic is far more complex that what you are making it out to be. what i was doing and i suspect Amirm is doing as well is playing devils advocate and saying that we do not have all aspects of Quantitative measurements of audio reproduction nailed down. just talking about the ability of a spaeker to "image" is a very loose thing. I do not see that measurement on my spec sheet...


What isn't complete, however, is a thorough understanding of our subjective preferences and perceptions of different kinds of stereo imaging.

this is what we are getting at, there are lots of isolated things that we can measure and loads of them interact with each other and you practically need a Phd in acoustics with a minor in physics to understand what they all mean.


And the answer is YES, it can be measured. It has been measured and studied, just not enough.

No argument at all. Complete agreement in fact. but if we do not have an easily read measurement/rating then we do not have a measurement.

The original point i was making is that we do not have everything solved. and yes, many of these things are perceptual. but if we came up with a standardized model of a room of a certain size and wall coverings of a certain definition, then i have a pretty good feeling that we could find a way to do tests, even DBT, where "imaging" could be rated on a 1-10 scale, we would get some pretty consistent results. And if we then took that "model" and started attacking it with science, and measurements, it is theoretically possible that someday we could have a rating where you know that these speakers "image" better than these based on a bunch of stuff. (please do not start going on about how different speakers are desgned for different types of rooms, etc.) and if we figured out what that magic combination was that equated to good imaging, we might also figure out that a higher % would equal better imaging, and a lower % would be poorer. and below a certain % (and above of course) makes no real difference. So our mythical testing means that we can measure levels that do or do not make a difference. and where a DBT might show no difference, well, we could measure a difference, but it is below the detectable range. so if i am a designer, i now go back to the drawing board with my Speaker Testing User Perception of Imaging Design tools software package and work on rev 2.


THe only point is that we do not have all the answers. so there is still much room in our beloved hobby for more interpretation. yes the stuff above is a silly pie in the sky example of such, but the point it still valid. if i look at some speakers, i would love to see a little more info that lets me know what to expect in my room.

here... can we all aggree on this.

IF a new test methodology comes up that can be shown to stand up to peer reviewed scrutiny... cool. lets take a look.

AND then... if that test methodology can be shown to correlate to hearing (DBT) then great.

If it stands up, but nobody can hear it, then it is not completely useless. it (as one part of a system) may be able to show aggregate things that are important and in the end DO stand up to DBT and the like.

But the claims in question in the OP... seem on the surface to be pretty outrageous.

A quick search within the AES library reveals a number of papers that discuss measuring stereo imaging. For example, the following 1989 paper; A Computer Model of Binaural Localization for Stereo-Imaging Measurement (http://www.aes.org/e-lib/browse.cfm?elib=5828)

It would seem that measuring stereo imaging is not a particularly challenging tasks, those precise co-relation to what we actually hear might be a different matter, but thats true of pretty much everything measurable in Audio anyway :)
Since Amir (as he frequently does when he is rabble-rousing) and Dizz have for some reason chosen to ignore this post, I'll quote it in its entirety. Please note the yr. With the advancements in computer modeling and understanding of human hearing in the past 20 yrs, this point is made even stronger.

However, I'm with Greg, I wanted to prove their findings....at the very least it would have made for an entertaining thread.

The topic is far more complex that what you are making it out to be.

I fully understand how complex it is, and I stated that explicitly: "What goes into imaging is very complex, and the number of measurements you'd need to take to characterize this perception is huge. There will never be any measurement of imaging because what constitutes good imaging is many things. It isn't a single variable, and any metric that includes all the variables that contribute to imaging would be a very subjective composite of many different measurement variables."

what i was doing and i suspect Amirm is doing as well is playing devils advocate and saying that we do not have all aspects of Quantitative measurements of audio reproduction nailed down. just talking about the ability of a spaeker to "image" is a very loose thing. I do not see that measurement on my spec sheet...

Again, this is a straw argument. You will never see such a measurement because it cannot be measured directly with a single specification. At BEST it might be characterized with some complex metric that involves a large number of measurements. The problem is that in the absence of such a simplistic specification of "imaging," that you're throwing into question whether something very clearly audible and audibly variable ("stereo imaging") is measurable. Amir is being playful, but unfairly so, in suggesting that in the absence of any common and simple specification that captures imaging, that therefore there are some weaknesses in our ability to measure speakers, and an inability to study objectively what contributes to speaker imaging. This is flatly false. The problem isn't in measuring the speaker, as I said. It is a problem in taking a plethora of measurements and finding some way to describe with some subjective metric our perceptions of a speakers imaging capabilities.

A parallel example would be for instance a way to characterize the sound of a particular tune of an instrument such as a piano or particularly organs (since they are often fixed more or less as built). As you may know, it is impossible to achieve a perfect tune on a fixed-tune instrument. It is physically impossible to do, and some notes inevitably will be imperfect. How that imperfection is distributed to certain notes more than others, or perhaps make everything sound slightly equally off, is a subjective choice that is forced by simple physics and the nature of the notes we have in the western scale.

There isn't any good way to characterize the complete sound of any one tune in a simple way, you'd have to measure each note and characterize how far off which notes are and by how much, and in that way you might capture what kinds of chords will sound more perfect on an instrument, and what chords will be more dissonant and disturbing. But saying that because this is a complicated thing to characterize, and a difficult thing to convey without a huge amount of measurements and a deep understanding of what they indicate, DOESN'T mean that it cannot be measured. There are an infinite number of ways to temper a tune, and you won't be able to find some number or figure or specification that will tell you what the tune of the instrument sounds like and what pieces of music will sound best on it. But the absence of such a simplistic metric doesn't mean it can't be done objectively.


this is what we are getting at, there are lots of isolated things that we can measure and loads of them interact with each other and you practically need a Phd in acoustics with a minor in physics to understand what they all mean.


I agree. But that's different than saying that there isn't a measurement of stereo imaging and insinuating that therefore we can hear something (stereo imaging) which cannot be captured by objective measurement.

It's like saying that protons and neutrons and electrons are questioned to exist because we don't have a scientific laboratory and as a layperson it's above my abilities to understand or test. That position simply doesn't follow. If SOMEBODY out there has the knowledge and experience and capabilities of capturing and studying stereo imaging, that capacity exists, regardless of whether it's an enormously complex task, or a simple singular measurement.

Even just asking what the frequency response of a loudspeaker is FAR more complex than you could ever include on even an entire sheet of paper. But you wouldn't then claim that you cannot measure frequency response because there isn't a singular specification that captures this in a complete way. We have an extremely simplistic common spec, measured usually on axis and close to the speaker at one SPL, which tells you a little bit, but it doesn't tell you a whole lot of things that are important to the real frequency response of the speaker under more complex conditions and in reality. But I wouldn't then say that because there isn't an easy way to capture FR across many angles and at many SPL and perhaps at varying distances (for some speaker designs this varies) that therefore FR can't be measured. That's fallacious and misleading.


No argument at all. Complete agreement in fact. but if we do not have an easily read measurement/rating then we do not have a measurement.

This is where I vehemently disagree.

See the above examples.

Think about contrast ratios on displays. There are an infinite number of real contrast ratios in real scenes, and the common on/off and ANSI CR-type measurements capture a very general idea of what the final image looks like, but there are many things they do not tell us that we clearly can see. Does this mean there are things we can see but we can't measure? No, because measuring an infinite number of CRs across all locations and varying images on a screen would be ridiculous. Likewise it is very difficult even for well-equipped people to measure very large contrast ratios (very low light is hard to measure accurately), differences which can be seen easily by the eye. But just because even relatively expensive equipment can't measure it easily doesn't mean it can't be measured or characterized.


The original point i was making is that we do not have everything solved. and yes, many of these things are perceptual. but if we came up with a standardized model of a room of a certain size and wall coverings of a certain definition, then i have a pretty good feeling that we could find a way to do tests, even DBT, where "imaging" could be rated on a 1-10 scale, we would get some pretty consistent results.

But even this is very complex, rather subjective, and very limited in applicability to very similar environments. Again my point is that these are difficulties of method, logistics, and to a certain degree difficulties of subjective perception of human subjects. They aren't fundamentally difficulties of measurement. Do you see the difference? They CAN be measured, it's just logistically difficult to do, and even more difficult is to "measure" the perceived impacts of what we measured objectively. Difficulty doesn't mean it can't be done.


And if we then took that "model" and started attacking it with science, and measurements, it is theoretically possible that someday we could have a rating where you know that these speakers "image" better than these based on a bunch of stuff. (please do not start going on about how different speakers are desgned for different types of rooms, etc.) and if we figured out what that magic combination was that equated to good imaging, we might also figure out that a higher % would equal better imaging, and a lower % would be poorer. and below a certain % (and above of course) makes no real difference. So our mythical testing means that we can measure levels that do or do not make a difference. and where a DBT might show no difference, well, we could measure a difference, but it is below the detectable range. so if i am a designer, i now go back to the drawing board with my Speaker Testing User Perception of Imaging Design tools software package and work on rev 2.


THe only point is that we do not have all the answers. so there is still much room in our beloved hobby for more interpretation. yes the stuff above is a silly pie in the sky example of such, but the point it still valid. if i look at some speakers, i would love to see a little more info that lets me know what to expect in my room.

I agree. We don't have all the answers about human perception, but that doesn't mean we don't have the ability to measure these things. That's the crucial difference.

Amir's argument doesn't lead to a conclusion that there are things we can hear but cannot measure. It only leads to the conclusion that there are things we can hear which are not completely perceptually modeled, and in any case are very difficult or impossible to characterize in a simplistic manner. Hence the absence of any simple "imaging" specification.

There is no specification that tells me what real scene contrast will be on displays. There are two common specifications that give me as an experienced videophile a general idea of how things might look depending on many factors. Doesn't mean that these things cannot be measured or that we've suddenly exceeded our capacity for measurement.

There is no complete specification on frequency response of a loudspeaker. Again, doesn't mean it cannot be measured.

There is no simple specification that tells you in any complete way what the tune of an instrument is and how that will sound. But it certainly can be measured. It can even be plotted visually, but you're talking about dozens of mapped points across a variety of chords, and you'd need to have a fairly good background in audio science to make heads or tails of it. But it COULD be done.

That's the problem I have with what Amir was saying was when he said: I did not demand a single number, only whether we can or cannot measure this effect. He clearly is insinuating that speaker imaging is something that even with very complex and thorough measurements, cannot be captured by measurement. That's simply not true.

Just because it cannot be reduced in a simple way, or is difficult to do, that doesn't mean it can't be done.

Since Amir (as he frequently does when he is rabble-rousing) and Dizz have for some reason chosen to ignore this post, I'll quote it in its entirety.
I am sorry. Didn't know anyone cared if I answered some post or not :).

Anyway, it is hard for me to comment on an abstract. I searched for a while but could not find the article. It is interesting to note what was said though:
"The results of the experiments detailed in the previous two sections have shown that the present binaural localization model is of use in measuring stereo imaging. Although exact correspondence between the judgements made by the computer model and those of human listeners should be confirmed by formal listening tests, the results are at least qualitatively those that are expected."
Without formal listening tests, it would be hard to put much weight on this. Computer models based on Binaural and HRTF have been around forever. The main use however, is not for measurement but rather to simulate things like surround sound with two channels. In that regard, accuracy is not paramount. Who is to know if the sound that came out at 3:00 o'clock, should have been at 5:00 o'clock?

Trying to use the same model for measurement though (and figure of merit as a result), would require far more accuracy.

Putting that aside, there is a lot more to stereo imaging than this type of analysis. Imagine how the sound stage would change in 3-d space if I added some echo to it. Inversely, if a playback system destroys the lower order resolution, and hence the reverberation clues, the sound stage will appear to collapse. The above models do nothing to quantify this effect. Yet this is an area of huge interest to high-end audiophiles.

Please note the yr. With the advancements in computer modeling and understanding of human hearing in the past 20 yrs, this point is made even stronger.
Actually I think the year makes the point much weaker. In the last "20 years" no one has taken that work and come up with any metric whatsoever in use for evaluation of stereo imaging. That should tell you how difficult it is to advance our understanding of how the human hearing system works.

Yes, there is a lot we know about how the ear works. But simple concepts like how we understand words, is completely without reach. Such is our perception of depth and sound stage in the context of complex music waveforms (although relatively speaking, much simpler than how we understand words).

Actually I think the year makes the point much weaker. In the last "20 years" no one has taken that work and come up with any metric whatsoever in use for evaluation of stereo imaging. That should tell you how difficult it is to advance our understanding of how the human hearing system works.

Perhaps it tells you less about how difficult it is, but more about how little monetary incentive there is to pursue it publicly. Companies spending lots of R&D dollars on designing high-performance speakers have little incentive to do give away all their research for free. And beyond that, who is going to fund this work publicly?

You're again finding conclusions that the evidence does not support.

I'm not saying it's not hard, but you're still saying "gee, I don't see a metric/research/understanding, therefore it MUST simply be too difficult and/or beyond our ability to measure or capture objectively!"

Maybe a more insightful interpretation would be that given the relative absence of public and in-depth research into stereo imaging, it shouldn't surprise anybody that we don't then have the kind of metric that captures that complexity in the way you desire...

Perhaps it tells you less about how difficult it is, but more about how little monetary incentive there is to pursue it publicly. Companies spending lots of R&D dollars on designing high-performance speakers have little incentive to do give away all their research for free.
Wouldn't it be great if we lived in a Utopian world where you could be free to go and use whatever a company or university student publishes in the public? Sadly, the reality is very different. Patent applications are universally filed prior to public disclosure and of course without due notice. You go and implement the idea, ship $100M worth of product and then you get a knock from a lawyer asking for 5% of your sales past and present.

So no, there is no practical risk of losing your IP this way.

And beyond that, who is going to fund this work publicly?
Well, having hired and managed countless PhD's and researched for our signal processing work in the past, I have to tell you that the reality is exactly opposite. Having peer recognition by having your paper published in a prestigious conference, has more cache than even salary to this class of people. You would not believe what it would take to not have them do this (i.e. because the patent app or provisional was not yet filed).

You're again finding conclusions that the evidence does not support.
I drew no conclusion other than stating the fact: there is no metric for measuring stereo imaging either in state-of-the-art instruments like Audio Precision or any published review. The only counter seems to be an abstract for a paper people have not read from 1989.

I'm not saying it's not hard, but you're still saying "gee, I don't see a metric/research/understanding, therefore it MUST simply be too difficult and/or beyond our ability to measure or capture objectively!"
Who said I am not seeing "research/understanding?" Certainly not me. There has been research forever in this area. But as I noted, the research is 99% directed toward other applications such as simulated surround/3-D audio. The other 1% is interesting but also enlightening as to how hard the problem remains. I am hopeful that we will some day get to a conclusion and have better metrics. But today is not it.

Maybe a more insightful interpretation would be that given the relative absence of public and in-depth research into stereo imaging, it shouldn't surprise anybody that we don't then have the kind of metric that captures that complexity in the way you desire...
Looks like the plot is lost here :). The original claim was that anything that can be heard in DBT, can be measured. I asked if stereo imaging differences can be heard. I didn't hear a counter so I assume we all agree that it can. If so, I asked how I go about measuring it. Your answer above seems to admit that we cannot but that we with more research we might. To which I say, fine, but sitting right here, I provided an example that proved the assertion wrong.

"We have previously identified three requirements for good imaging. the sound from each speaker must arrive with the same:

1. Frequency Response
2. SPL
3. Time Arrival"


Comments?

Here two brothers are working and have developed technology to get an out of head "image" from headphones (as I recall I first learned about this techology in "Widescreen Review"). It would seem to me a lot of work has been done to better understand what is needed to "image" a music or movie source.
http://www.smyth-research.com/technology.html

Here two brothers are working and have developed technology to get an out of head "image" from headphones (as I recall I first learned about this techology in "Widescreen Review"). It would seem to me a lot of work has been done to better understand what is needed to "image" a music or movie source.
http://www.smyth-research.com/technology.html
I was doing a keynote at AES UK last year and ran into these folks. I have listened to it and it is startling how well it works. You put on a headphone and then they switch between 5 speakers and the headphones and you almost can't tell the difference (they use open Stax Electrostatic headphones). It is very well done. The key inventor by the way was the guy who designed DTS audio codec.

The headphone has a positional sensor which the main controller uses to steer the audio as your head moves. They also perform correction so that the headphones sound the same as the speakers. The sensor deals with the fact that typical HRTF based systems assume an average head positioned certain way. Knowing which way your head is pointed is a huge help here in creating a more realistic field.

They are targeting pro applications due to high cost.

I was doing a keynote at AES UK last year and ran into these folks. I have listened to it and it is startling how well it works. You put on a headphone and then they switch between 5 speakers and the headphones and you almost can't tell the difference (they use open Stax Electrostatic headphones). It is very well done. The key inventor by the way was the guy who designed DTS audio codec.

The headphone has a positional sensor which the main controller uses to steer the audio as your head moves. They also perform correction so that the headphones sound the same as the speakers. The sensor deals with the fact that typical HRTF based systems assume an average head positioned certain way. Knowing which way your head is pointed is a huge help here in creating a more realistic field.

They are targeting pro applications due to high cost.I met them and actually have the system. Nice guys too!

Anyway, it is hard for me to comment on an abstract. I searched for a while but could not find the article. It is interesting to note what was said though:


I think your argument that stereo imaging cannot be measured, or that theres no single metric for stereo imaging is pretty weak.

Theres no disagreement that many factors contribute to the perception of stereo imaging. There can also be no argument that stereo imaging is a "perception", in that it happens inside the head.

Since we can't actually measure whats happening inside our heads. The only avenue available is to measure the contributing factors to stereo imaging.

One could argue that we don't know about all such contributing factors. Nevertheless, roughly going through many of the AES papers related to measuring stereo imaging, it becomes quite clear that easily much of the contributing factors can and have been measured.

What remains subjective however is the "in-head" model of how these factors are combined to produce the illusion of stereo imaging.

By the way, I would have assumed you had access to the AES papers, seems I was in error - doesn't take much to be a subscription member.

I think your argument that stereo imaging cannot be measured, or that theres no single metric for stereo imaging is pretty weak.
Once more, I point to factual things that are quite strong. No instrument measures it. No reviewer uses it. No equipment maker advertises it. None of these are "arguments." They are facts.
What remains subjective however is the "in-head" model of how these factors are combined to produce the illusion of stereo imaging.
Yup. And if you can't measure that, then you can't tell me that you can match 1:1, the observations of real people in DBT as NIN claimed. After all, the people in DBT don't hear the components but perceive the sum total.
By the way, I would have assumed you had access to the AES papers, seems I was in error - doesn't take much to be a subscription member.
I don't work for anyone right now so have no need to subscribe. But we did have it when I worked for Microsoft. I don't miss a lot regarding working for big companies, but access to such things is one of the exceptions :).

Fortunately, a lot of papers find their way to the web to satisfy my casual curiosity these days.

I met them and actually have the system. Nice guys too!
You lucky dog you! :D They are very nice people. I must spent a couple of hours with them comparing notes in working with CE companies, getting design wins for codecs and such.

I think your argument that stereo imaging cannot be measured, or that theres no single metric for stereo imaging is pretty weak.

Theres no disagreement that many factors contribute to the perception of stereo imaging. There can also be no argument that stereo imaging is a "perception", in that it happens inside the head.

Since we can't actually measure whats happening inside our heads. The only avenue available is to measure the contributing factors to stereo imaging.

One could argue that we don't know about all such contributing factors. Nevertheless, roughly going through many of the AES papers related to measuring stereo imaging, it becomes quite clear that easily much of the contributing factors can and have been measured.

What remains subjective however is the "in-head" model of how these factors are combined to produce the illusion of stereo imaging.

By the way, I would have assumed you had access to the AES papers, seems I was in error - doesn't take much to be a subscription member.
As if all perception of sound doesn't take place in your head.

Looks like the plot is lost here :). The original claim was that anything that can be heard in DBT, can be measured. I asked if stereo imaging differences can be heard. I didn't hear a counter so I assume we all agree that it can. If so, I asked how I go about measuring it. Your answer above seems to admit that we cannot but that we with more research we might. To which I say, fine, but sitting right here, I provided an example that proved the assertion wrong.

Amir, stop being dense.

You clearly insinuated that stereo imaging cannot be measured, or in other words cannot be captured in measurement. That is clearly wrong. (I directed you to Floyd Toole's work in exploring what aspects of speaker performance impact imaging and how that is perceived by listeners. He has a whole section in his book on it, and it's quite interesting.) To support this point (that it cannot be measured) you used a sleight of hand argument that the absence of any common specification for "stereo imaging" supports your claim that it cannot be measured. And that is false logic.

So to get back to the original question which you continue to obfuscate, can speaker imaging be measured. And the answer is clearly yes. Is speaker imaging measured? No. That's a different question.

I would argue that frequency response isn't usually measured either (in any realistically in-depth way that actually gives you anything but the most cursury glimpse), but that doesn't mean that the FR of a loudspeaker is somehow not measurable.

Can speaker imaging be measured: YES. Period.

You're basically sitting here saying "well gee, there's nobody on the moon right now, there's nobody on a mission to the moon, and no missions are being planned, therefore it's not possible to go to the moon." "gee, I don't see any measurements of speaker imaging, therefore it can't be done."

Once more, I point to factual things that are quite strong. No instrument measures it. No reviewer uses it. No equipment maker advertises it. None of these are "arguments." They are facts.

That's BS and you know it. Yes those are facts, but they are irrelevant facts. Pepperoni pizza is made with pepperoni and that's a fact, but that has as much relevance in proving your point as any of those assertions do.

Here, let me put your argument another way:

There is no specification that captures the instantaneous contrast ratios of two locations in a real image on video displays. Therefore, contrast ratios cannot be measured on video displays.

Do you agree or disagree with my claim that contrast ratios cannot be measured on video displays?

Once more, I point to factual things that are quite strong. No instrument measures it. No reviewer uses it. No equipment maker advertises it. None of these are "arguments." They are facts.



All the key properties of sound reception that contribute to the perception of a stereo image can and have been measured. They're not one measurement, but multiple. That is a fact.

You're right in that theres no single instrument that measures all these properties and combines them into a single stereo image picture, but thats a separate issue from the ability to measure each individual property that contributes to the final stereo image.

Just as there are no single instruments to measure an optical illusion or a 3-dimensional view, yet we can plainly measure all the key properties of such visual images and reproduce them at will without needing that one instrument or one metric.

Obviously you're arguing for argument sake, not much point in me repeating myself.

You're right in that theres no single instrument that measures all these properties and combines them into a single stereo image picture, but thats a separate issue from the ability to measure each individual property that contributes to the final stereo image.
Again, where did I say I was interested in "individual property that contributes to the final stereo image?" This is all I said in my original post:
What is your opinion of stereo imaging? That it can be measured or that it cannot be heard in DBT?
I am looking to see what measurement leads to me to the same results as DBT. If I can do that, then I don't need to perform DBT to determine stereo imaging of a system. Is your assertion that we are already there since we know "all" key contributions to stereo imaging?
Just as there are no single instruments to measure an optical illusion or a 3-dimensional view, yet we can plainly measure all the key properties of such visual images and reproduce them at will without needing that one instrument or one metric.
I didn't ask you for a single number. I asked you if you can show with measurements exactly the same results achieved in DBT. It is a simple question and should have a simple answer if you are correct that all we need to know is already known.

BTW, the eye and ear work very differently in how the perceive depth. For example, slight movements in your head help you with localizing the sound. That does nothing for your eyes. It is these kinds of complexities which make the problem so much harder.
Obviously you're arguing for argument sake, not much point in me repeating myself.
Look, we are all here to "argue" so please let's not state the obvious :). Everyone knows that already :D.

This is a strange discussion though as both you and Chris are agreeing with the top level assertion that we cannot yet measure how the brain perceives stereo imaging. On my side, I agree that some (but not all) of the major contributors factors can be measured. Where we are falling apart is that you stop at the contributing factor and don't want to go the extra mile and answer the original question I asked. Can I, using measurements, explain the exact results achieved through DBT test of stereo imaging? I have said no. Such a measurement, whether it is one or more numbers does not exist.

Pepperoni pizza is made with pepperoni and that's a fact, but that has as much relevance in proving your point as any of those assertions do.
Rats. You took my next argument away :D.

Here, let me put your argument another way:

There is no specification that captures the instantaneous contrast ratios of two locations in a real image on video displays. Therefore, contrast ratios cannot be measured on video displays.

Do you agree or disagree with my claim that contrast ratios cannot be measured on video displays?
There may not be a specification that is in use because it is not a useful thing to measure. But I do have the ability to measure the contrast difference between two points by using two separate instruments and arrive at the exact data you are asking about. I don't know how to measure how you perceive stereo imaging even if I used 100 instruments.

In sharp contrast, pun intended :), we are very interested in having instrumentation that tells us what we hear. DBT tests are super expensive, take forever to run and are subject to incorrect results. So the fact that we have not yet achieved a measurement for it, despite huge interest in the industry and consumer eyes, is far more than "BS." Companies like Audio Precision sell $25,000 audio instruments. If they could even come close to new measurements like this, their fortunes would double and triple in no time.

Rats. You took my next argument away :D.


There may not be a specification that is in use because it is not a useful thing to measure. But I do have the ability to measure the contrast difference between two points by using two separate instruments and arrive at the exact data you are asking about. I don't know how to measure how you perceive stereo imaging even if I used 100 instruments.

I already cited Floyd's chapter which cites numerous papers which explore what contributes to imaging quality. You would measure primarily the dispersion characteristics of the speaker, and the freq response of off-axis sound compared to the on-axis sound.


In sharp contrast, pun intended :), we are very interested in having instrumentation that tells us what we hear. DBT tests are super expensive, take forever to run and are subject to incorrect results. So the fact that we have not yet achieved a measurement for it, despite huge interest in the industry and consumer eyes, is far more than "BS." Companies like Audio Precision sell $25,000 audio instruments. If they could even come close to new measurements like this, their fortunes would double and triple in no time.

As I've been saying THIS IS ALREADY BEING MEASURED. The work that I cited has long been taken into account in the design of hifi loudspeakers. Good speaker designers are designing many speakers with the kind of wide and even dispersion without off-axis coloration that leads to a broad sense of stereo imaging, and acousticians place dispersion at reflection points in the design of many listening rooms again due to what has been measured and understood about how we perceive stereo imaging.

Why do you continue to ignore these facts?

You continue your claims that we can hear things in DBT that can't be measured. That may be true in some other domain, but it is absolutely factually NOT true when it comes to basic stereo imaging because it has been done and I'm sure it continues to be done by speaker manufacturers and this understanding based on measurement guides design choices.

Why do you continue to ignore these facts?

In his defense, you are ignoring who he is antagonizing. You are just collateral damage. His argument is that there is no measurement you can use, that once applied, a listener could not differentiate through a DBT. This is true of many aspects of speakers. The argument does not suggest that you cannot have metrics that give a good understanding of a speaker's imaging (i.e. a good audio engineer would be able to tell from a number of well selected metrics whether a speaker would image poorly or well). Sometimes he overstates his case to annoy, but the fact does remain, given the metrics, one cannot guarantee that it would pass a DBT. However, it could tell you a if speaker stinks or excels at imaging.

Given enough practice, one day Amir will be to many here what John (Alimental) was to Greg. The difference is that he can multitask (i.e. he does not limit himself to just one "prey").

In his defense, you are ignoring who he is antagonizing. You are just collateral damage. His argument is that there is no measurement you can use, that once applied, a listener could not differentiate through a DBT. This is true of many aspects of speakers. The argument does not suggest that you cannot have metrics that give a good understanding of a speaker's imaging (i.e. a good audio engineer would be able to tell from a number of well selected metrics whether a speaker would image poorly or well). Sometimes he overstates his case to annoy, but the fact does remain, given the metrics, one cannot guarantee that it would pass a DBT. However, it could tell you a if speaker stinks or excels at imaging.

Given enough practice, one day Amir will be to many here what John (Alimental) was to Greg. The difference is that he can multitask (i.e. he does not limit himself to just one "prey").

That's not the way I interpret what he's said at all. He's been quite clear and explicit that he does not think that speaker imaging is measurable.

That's not the way I interpret what he's said at all. He's been quite clear and explicit that he does not think that speaker imaging is measurable.
I have not said anything about measuring "speaker imaging." I am talking about the broader measurement of stereo imaging which goes beyond just the speaker. I gave an example of joint stereo effect to show that it can occur upstream of the entire audio playback chain.

For another example, imagine if the level of crosstalk in an amp increases on transients. So for that moment in time, your stereo image collapses by some unknown amount. Imagine what happens if I butcher the low order 2 bits of your audio samples once in a while. When I do that, you lose the sense of depth because low level reverberations are lost that way.

The reason all of the above comes into play is that I am not trying to evaluate speakers but measure, what has been heard in a listening test which includes everything in the chain.

More importantly, since double-blind tests are not conducted in outer space, then the room comes into play. So certainly you can't stop at the anechoic measurements (or even reverberant in another room) to explain the results of a double blind test as was claimed.

Further, I am not looking for any measurement but one that 1:1, correlates with listening tests. It is not sufficient to have gross measurements of some speaker characteristics (Raul's point) because they would not match the results of subjective tests as was claimed.

I already cited Floyd's chapter which cites numerous papers which explore what contributes to imaging quality. You would measure primarily the dispersion characteristics of the speaker, and the freq response of off-axis sound compared to the on-axis sound.
Mentioning some chapter without specifics is not "citing" anything. I just read the measurement chapter for a second time including the list of 46 references. Nothing jumped out as the measurement for stereo imaging. This, despite practically dozens of different measurements mentioned in the book. So if there is a specific mention, by all means, tell me what that is so that I can comment on it. Until then, there is nothing that confirms your position that we can measure all of this precisely.

Following that chapter though, there is an entire one on subjective testing. This is how it starts: "A loudspeaker isn’t good until it sounds good." Do you think stereo imaging is a contributor to a speaker sounding good? If so, you have Flyod telling you that you can measure all you want but listening tests is what ultimately counts. He then goes to say this in the conclusion section of the same chapter:

"Listening evaluations are routine in the audio industry. They remain the final arbiters of sound quality."

So the final arbiter is listening test and not the measurements. So surely, logic follows that if you inverse this statement, it would not be true. That is, you can't claim that everything that can be heard in DBT can be measured.

Section 3.3.3 is the only place where there is mention of stereo imaging. Here is how it starts;

"Because the choice of possible arrangements is so wide, it seems particularly desirable to try to establish at the outset just what directional characteristics loudspeakers should have in order to give the most natural and pleasing reproduction of well-recorded music. No single recipe can be confidently stated to be universally right, partly because personal preferences are inherently involved, but also because the optimum directional characteristics are very considerably influenced by the acoustics of the room in which the loudspeakers will be used. However, by using scientific reasoning whenever possible, combined with careful experimenting and critical subjective comparisons between reproduced and live music, a number of guiding principles have emerged."

Note the phrase, "guiding principal." There is a hell of a distance between that phrase and us knowing enough to predict the results of listening tests when it comes to directionality.

He goes to say this:

"Thus the second guiding principle to emerge is that the axial frequency response of any loudspeaker at normal listening distances should be approximately level."

"Should?" "Approximately?" How can these be taken as precise things?

This is what he says about performance in reverberant (typical) rooms:

"Clearly, to minimize the disturbing influence of wall reflections, loudspeaker output in directions well off-axis should, in general, be as small as possible, though the need for this feature is very dependent on the conditions of use."

"Generally?" "Very depending on condition of use?" He follows with this:

"Thus the third guiding principle to emerge is really an extension of the first, and is that the increase in directivity with rising frequency should not only be reasonably mild in degree, but should also occur in a smooth and continuous manner, and should be accompanied by off-axis frequency responses that are devoid of ‘unnatural’ features."

Since when "guiding principle" become a precise metric? I let you figure out what "unnatural features" mean :p.

He then sums it up this way:

"Taking all aspects into account, it is evident that some loudspeaker directivity is always desirable, but that the nature of this directivity needs to be rather carefully controlled, both for good stereo imaging, and to avoid an unpleasant or unnatural quality in the overall sound received by listeners."

Tell me where in that statement he is talking about a precise measurement. "Some directivity" is given as general rule, not a specific number to shoot for.

I could go on with many more quotes like this. But as you see, while there are a ton of wisdom and experience translated into words in this book, there is not anything remotely matching what I was looking for. Namely, being able to measure stereo imaging that is heard in a real room in a double-blind test.

Further, I am not looking for any measurement but one that 1:1, correlates with listening tests. It is not sufficient to have gross measurements of some speaker characteristics (Raul's point) because they would not match the results of subjective tests as was claimed.Well, why does it have to correlate 1:1? It can be a fuzzy number that correlates with say 60% of the population would find. That'd be enough to influence sales.

Well, why does it have to correlate 1:1? It can be a fuzzy number that correlates with say 60% of the population would find. That'd be enough to influence sales.
No argument. Indeed, we could compute the upper bound.

Assuming HRTF and Binaural techniques are used, then we can assume that an average sized manikin and torso would be around the measurement device. Such a model is unlikely to be representative of more than 80% of the population. Inverted, 20% of the people would have different enough head shape, ears, etc. to not hear the same.

Then we would have to put some bounds on what we are computing. Assuming 10% error there we are down to 70%.

Assuming 10% of the people would prefer something even though not as good, and we would be at your 60% number :).

burden of proof falls on you. Show us how you measure it. Lack of something can not be proven.


No, not at all :)

For instance, did you mean that if somebody can pass a test that 2 things are different we are then capable of doing measurements that show that the 2 things are actually different, or that we can do measurements that 2 things are different and characterize what that means to how people will perceive them (which seems to be the way that Amir took it)?

--Darin


The first of course :)

No, not at all :)
NIN, do you know why the burden of proof for cable differences falls on the claimant? The reasons are numerous, but you can narrow them down to two basic ones. Extraordinary claims must be proven and one cannot prove a negative so it is incumbent on the claimant to provide proof. You claimed a metrics existed for imaging that met the threshold for a DBT. The task for you is simple, either produce the metrics or provide a citation. You merely waving your hands and talking like a parrot is the type of argumentation subjectivists wallow in. There is another thread in which you exhibited this exact tendency and it served you poorly, so it makes little sense to attempt to use the same strategy again. If you are not able to hold your side of the bargain, at the very least do not use the same argumentation style that you have been so critical of in the past (and will be against in the future).

Raul, please read what Chris already have written.

You claimed a metrics existed for imaging that met the threshold for a DBT.


Please show me the quote I say that.

Raul, please read what Chris already have written.

Chris feels imaging is measurable and he made his case by tangible examples. In other words he made an effort to substantiate his arguments.

This is very different than saying "you are wrong and I am right until you prove me wrong".

I don't have any problem with your end point, you may as well be right and imaging can be measurable. Your discussion methodology is less than ideal though.

You claimed metrics existed for imaging that met the threshold for a DBT.

Please show me the quote I say that.

There are good methods to measure already. I have never seen even one audiophile that even once proven something in a DBT that we cannot measure without a problem.

If it can be proven in a DBT it can be measured.

as amirm keeps mentioning, how do we measure imaging? we cant.

Do you have any proof of this? As it have been said before, if you can hear it it can be measured.

Backpedaling and obfuscation works a lot better when you don't leave evidence all over the place, especially in your very first few posts in this thread.

what is funny is that i came up with a very broad "imagine if" as an example of an area where there is no measurement that can show up on a spec sheet, that it would be great if somebody did manage to find a way to apply a metric to.

the amount of digging into ratholes, and other esoteric discussions that have come up are mind boggling.

Simple put, we have the ability to measure almopst everything about the sound that comes out of a speaker.

we DO NOT have the ability to correlate all of that into how it relates to how we hear. (the bass is warmer, the midrange is more expansive, the soundstage was huge) we can nail down parts of it, but our lexicon is missing some key descriptors.

So my point at the beginning was simply to say that if somebody comes up with something, and they can document it, back it up, and allow it to stand up to peer review, then hey, maybe the next generation of measurements may appear one day.

BUT THIS ONE IS NOT IT!

Backpedaling and obfuscation works a lot better when you don't leave evidence all over the place, especially in your very first few posts in this thread.


Where did I say there is a metrics in those quotes? :confused:

Let's start with nin's original statement:

If it can be proven in a DBT it can be measured.

What does 'proven in a DBT' mean? Well it means that the test taker was able to determine differences between condition A and condition B (statistically significant). amirm then challenged nin's statement by asking him:

What is your opinion of stereo imaging? That it can be measured or that it cannot be heard in DBT?

First, what would a dbt be for stereo imaging? Do you know if one could pass a dbt on stereo imaging? Let's assume one could therefore something would have to be changed between condition A and condition B to affect stereo imaging so as to pass a dbt (for example speaker spacing).

I will bet everytime one is able to pass the dbt on stereo imaging we will be able to measure changes in many different areas of the the sound/signal. Do we have one metric to measure--no, but that is not the issue. The issue is whether or not we can measure any differences in the sound. Does anyone want to argue this is not true?

The audiophile's postition is that we can not measure everything relating to sound and therefore many tweaks and accessories make a difference even if 'currently' immeasurable.

The proof of this will be when one person can pass a dbt but our current methods of measurement detect no difference between the two conditions. We are still waiting for this to happen....

BTW, we can construct dbt's that humans can not pass yet there are measurable differences in condition A and B. They are called hearing tests and people fail them every day...

I will bet everytime one is able to pass the dbt on stereo imaging we will be able to measure changes in many different areas of the the sound/signal. Do we have one metric to measure--no, but that is not the issue. The issue is whether or not we can measure any differences in the sound. Does anyone want to argue this is not true?
Sure, we can measure the differences. But where would we start? What would we measure and why? What if the effect we are looking for is stereo separation in an amp collapsing by 10 db, from 15 Khz to 20 Khz, for 10 ms during a transient? How would you have known to look for that if I didn't give you this information? The measurement "set" is infinite here. So it is not sufficient to say there is some measurement, some place, that might do this.

This of course, is putting aside that we are looking for a figure of merit to track DBT results not just the fact that we can measure that something has changed. That is, the higher the number, the better the system in this regard. We are looking for useful measurements, not pure differential measurements. The former lets us improve products without the expense of double-blind tests.

In other words, the measurement of interest would prove why in DBT, preference was put on one set of changes and not others. In both cases, there will be differences. So measuring that is not very useful.

The audiophile's postition is that we can not measure everything relating to sound and therefore many tweaks and accessories make a difference even if 'currently' immeasurable.
The former is not just the position of audiophiles but researchers and engineers alike. Every lossy audio codec for example, has a psychoacoustics model of human hearing system created by people with most knowledge in that area. Yet, there is not a single lossy codec that is not designed and optimized without extensive listening tests and reliance on "expert listeners." This is true of major companies and their research arms and international standards groups such as MPEG. "Tweaks" in the coding system are always verified and proven with listening tests and not relied upon just because someone theorizes based on human hearing system that it is going to be better.

The proof of this will be when one person can pass a dbt but our current methods of measurement detect no difference between the two conditions. We are still waiting for this to happen....
That topic has nothing to do with what we are discussing here. Here, we are trying to prove or disprove the assertion that if you can hear in DBT, you can measure it. I asked if we can hear differences in stereo imaging. I think we can all agree that we can for many scenarios there. I say that we do not yet have measurements that can produce the same results using instruments. That is a measurement that goes up with preference in DBT, and goes down with opposite results (i.e. tracks/correlates with real world results).

Like Dizz, I continue to be amazed that there is so much push back here. The example I picked is a super difficult case and I thought would bring clarity to why NIN's generalization was not thought through and wrong in many, many cases.

The audiophile's postition is that we can not measure everything relating to sound and therefore many tweaks and accessories make a difference even if 'currently' immeasurable.

i am far from an audiophile. I would easily say that we can measure all the sound. but i would also say that we cannot yet interpret it all to meaningful data that correlates to what we hear.

That area still has plenty to figure out.

If I follow amirm correctly, he is saying that we don't have a measurement that will reliably be able to always determine which of two setups has the better imaging. Not that we can't see a difference between setups that have differences in imaging. (At least I hope that's not he means. If it is, I can assure that technologically finding differences in two different setups is very easy.)

A problem with the whole concept of preference, though, is that people won't reliably agree on which equipment has the better quality X (imaging, or whatever). Given that, I can't think of a way a measurement could discern the better setup in agreement with listening, unless what is "better" can be pretty universally agreed upon.

-an occasional lurker on this board

Sure, we can measure the differences. But where would we start? What would we measure and why? What if the effect we are looking for is stereo separation in an amp collapsing by 10 db, from 15 Khz to 20 Khz, for 10 ms during a transient? How would you have known to look for that if I didn't give you this information? The measurement "set" is infinite here. So it is not sufficient to say there is some measurement, some place, that might do this. Are you in possession of some information about a particular receiver that does this?

Are you in possession of some information about a particular receiver that does this?
I have not measured my amps to know if I do or do not. But I can explain how it might occur.

In an ideal world, a two-channel amp would act like two fully independent amps. Each would amplify the signal sent to regardless of what the other amp would do. In that case, channel separation would be infinite.

But many stereo amps share a power supply. So there is a lead that goes directly from one amp to the other. If the power supply is fully decoupled and has infinite capacity, that should not cause much problem either. But real life is not that way. Many amps, especially the lower-end ones, do not have infinite power evidenced by the fact that if you measure the power coming out of both channels simultaneously, is lower than if you measured the power in each one independently.

Now as it turns out, amps tend to have lower channel separation at higher frequencies to start. Here is a quick example I found on the net for a Parasound amp:
http://theaudiocritic.com/cwo_images/image122.jpg
The curves will vary but they always get worse at higher frequencies. Here is a Denon for example:
http://www.audioholics.com/reviews/amplifiers/denon-poa-a1hdci/Xtalk.JPG/image

60 and 70 db are far below infinite.

So now, put two and two together. Assuming that we have a transient that bangs on the power supply. That will cause crosstalk to increase. And since high frequencies is where we have the most leakage possibility, it would be plausible to assume that its level would rise up to a level which is more audible than other areas which are not.

So maybe audiophiles are not so crazy, buying mono "blocks" or overdesigned amps with independent amps in one box. No? :)

I have no problem with mono-amps but I was hoping you could come up with a real-life measurement on some receiver to illustrate your point with respect to channel separation. It's a bit hypothetical right now.

I have no problem with mono-amps but I was hoping you could come up with a real-life measurement on some receiver to illustrate your point with respect to channel separation. It's a bit hypothetical right now.
Not nearly as hypothetical as saying anything we hear in DBT can be measured ;) :).

I will bet everytime one is able to pass the dbt on stereo imaging we will be able to measure changes in many different areas of the the sound/signal. Do we have one metric to measure--no, but that is not the issue. The issue is whether or not we can measure any differences in the sound. Does anyone want to argue this is not true?


I agree.

I have not measured my amps to know if I do or do not. But I can explain how it might occur.

In an ideal world, a two-channel amp would act like two fully independent amps. Each would amplify the signal sent to regardless of what the other amp would do. In that case, channel separation would be infinite.

But many stereo amps share a power supply. So there is a lead that goes directly from one amp to the other. If the power supply is fully decoupled and has infinite capacity, that should not cause much problem either. But real life is not that way. Many amps, especially the lower-end ones, do not have infinite power evidenced by the fact that if you measure the power coming out of both channels simultaneously, is lower than if you measured the power in each one independently.

Now as it turns out, amps tend to have lower channel separation at higher frequencies to start. Here is a quick example I found on the net for a Parasound amp:
http://theaudiocritic.com/cwo_images/image122.jpg
The curves will vary but they always get worse at higher frequencies. Here is a Denon for example:
http://www.audioholics.com/reviews/amplifiers/denon-poa-a1hdci/Xtalk.JPG/image

60 and 70 db are far below infinite.

So now, put two and two together. Assuming that we have a transient that bangs on the power supply. That will cause crosstalk to increase. And since high frequencies is where we have the most leakage possibility, it would be plausible to assume that its level would rise up to a level which is more audible than other areas which are not.

So maybe audiophiles are not so crazy, buying mono "blocks" or overdesigned amps with independent amps in one box. No? :)

amir,

are there any particular real life situations that you feel monoblocks are beneficial? Or do you believe they are good to have no matter what?

i think that what he is saying is that there are arguments that can be made. there is a theoretical advantage shown there. how much this translates to audible issues... well that is not part of the conversation.

Any performance phenomena significant enough to be audible (a well-done DBT can be a good method for determining this) can be identified and measured or characterized.

amir,

are there any particular real life situations that you feel monoblocks are beneficial? Or do you believe they are good to have no matter what?
There is no question that all else being equal, a mono block has better performance due to complete isolation of components. Of course, that also comes at high cost so if price/performance is an issue, then I would look at well designed multi-channel amps which have power supplies sized to full rated output across all channels. What you don't want is something like this Sony AVR:

http://www.soundandvisionmag.com/assets/image/2009/W13/3272009171825.jpg

In general, the more power you suck out of the amp, the more you want it be over designed/isolated/mono-block to eliminate crosstalk through power supply rails. Inefficient/full-range speakers would fall in this category.

Anyone else has some thoughts on this front?

.... Here, we are trying to prove or disprove the assertion that if you can hear in DBT, you can measure it. I asked if we can hear differences in stereo imaging. I think we can all agree that we can for many scenarios there. ....

Well, it would be better to demonstrate that this, in fact, is the case under controlled conditions, like DBT, etc, and not because the separation collapses by 10dB for x ms at x FR band or any other scenario. I'd be most interested in those DBt tests.

Well, it would be better to demonstrate that this, in fact, is the case under controlled conditions, like DBT, etc, and not because the separation collapses by 10dB for x ms at x FR band or any other scenario. I'd be most interested in those DBt tests.
You ask a hard question. Indeed, it was the same question I asked when I started the rat hole :). There are infinite scenarios for stereo imaging to change. Some of which will be audible to all, some will be audible to some, some will be audible to none! Just going through all of those scenarios in DBT will take a lifetime or more leaving us no time to actually go back and figure out how to justify them using measurements. I did say I picked a complex example to make a point, did I not? :D

BTW, have you ever driven around, listening to a weak FM station and noticing that stereo imaging changes, sometimes collapsing to mono and back?

There is no question that all else being equal, a mono block has better performance due to complete isolation of components. Of course, that also comes at high cost so if price/performance is an issue, then I would look at well designed multi-channel amps which have power supplies sized to full rated output across all channels. What you don't want is something like this Sony AVR:

http://www.soundandvisionmag.com/assets/image/2009/W13/3272009171825.jpg

In general, the more power you suck out of the amp, the more you want it be over designed/isolated/mono-block to eliminate crosstalk through power supply rails. Inefficient/full-range speakers would fall in this category.

Anyone else has some thoughts on this front?

Assume you have relatively less demanding speakers. If you match them with a competently designed multi-channel with abundantly more power than they require for each channel, will you still benefit from replacing multi-channel with monoblocks?

Assume you have relatively less demanding speakers. If you match them with a competently designed multi-channel with abundantly more power than they require for each channel, will you still benefit from replacing multi-channel with monoblocks?
I personally stop at that level, as evidenced by my Proceed 5 channel amp. At work though, when budget was no object :D, we had Mark Levinson mono-blocks. The cool factor they brought as they say, was priceless :).

Somewhat related, I very much like separate amps (and hence electronic crossovers) for bass and mid/highs. This way, if the amp runs out of juice, it doesn't bleed into tweeter and make things harsher. For my second theater, I am considering Wisdom speakers with dual amps per channel. I run all of my studio monitors that way and it is a very nice way to go (although their built-in amps often don't have the quality they should).

Ah, the old "monoblock" argument. I would say that most good stereo amplifiers have so low cross-talk that it is not an issue. But if one could prove it in a DBT I would like to see it :)

Ah, the old "monoblock" argument. I would say that most good stereo amplifiers have so low cross-talk that it is not an issue. But if one could prove it in a DBT I would like to see it :)

A variable that is not scientifically measured can still have a material impact on the outcome. Lack of a measurement does not suggest insignificance of the subject variable. It suggests lack of observation about the significance of the subject variable.

Earth was round even before science proved that it was.

BTW, have you ever driven around, listening to a weak FM station and noticing that stereo imaging changes, sometimes collapsing to mono and back?

That's just the agc turning off the stereo demodulator when the 19kHz sub-carrier is too weak or loosing phase-lock on the carrier.

Typical chip. http://www.datasheetpro.com/node/115533

That's just the agc turning off the stereo demodulator when the 19kHz sub-carrier is too weak or loosing phase-lock on the carrier.

Typical chip. http://www.datasheetpro.com/node/115533
That is the cheap way of handling it. More advanced stereo decoders adaptively filter high frequencies and how they apply L-R to create the stereo channels. That avoids the scratchy sound you get from multi-path distortion and switching back and forth to mono.

Putting aside the nuts and bolts, the reason I mentioned that is that we have a good example of dynamic stereo imaging. The effect is clearly audible. But if I didn't tell you how it worked, you would be scratching your head, wondering how you would characterize it. Moreover, you could get people who were annoyed with adaptive mode above, and just wanted to hear the mono version. Whereas a bunch of people would think the opposite.

A variable that is not scientifically measured can still have a material impact on the outcome. Lack of a measurement does not suggest insignificance of the subject variable. It suggests lack of observation about the significance of the subject variable.


I'm waiting :)

A variable that is not scientifically measured can still have a material impact on the outcome. Lack of a measurement does not suggest insignificance of the subject variable. It suggests lack of observation about the significance of the subject variable.

Earth was round even before science proved that it was.

He was talking about crosstalk, which actually can be measured. Good engineering can make it a non-issue as well.

BTW, have you ever driven around, listening to a weak FM station and noticing that stereo imaging changes, sometimes collapsing to mono and back?

Having stereo derived from a mono L+R signal and an L-R DSB subcarrier is not quite the same as having two discrete (L and R) signals. A well-designed stereo FM receiver will not make stereo when the signal is not strong enough to extract a good L-R. Of course that will affect stereo imaging.

I was wondering when B-Lee from QSC would arrive on the scene!!!

Good to see ya Bob.

Having stereo derived from a mono L+R signal and an L-R DSB subcarrier is not quite the same as having two discrete (L and R) signals.
Actually, it is exactly the same if you can reproduce both signals perfectly:

(L+R)+(L-R) = 2L
(L+R)-(L-R) = 2R

Divide the two numbers by 2 and you get L and R as if they were sent separately.

For those not familiar with how FM stereo works, to maintain backward compatibility with then mono system, L+R is transmitted in the mono channel and L-R is additionally transmitted. A mono radio ignores L-R but a stereo radio will also receive that and using the above math, arrive at the separate channels. This is how we get color in analog TV systems (similar compatibility issue with black&white TVs).
A well-designed stereo FM receiver will not make stereo when the signal is not strong enough to extract a good L-R.
A well-designed system will make the best of what it has available to it and not give up simply due to a signal threshold not met as you describe. The system is adaptive and will not just switch on and off to mono. Furthermore, as I noted, multi-path distortion can wreak havoc with stereo reproduction so a good system takes that into account also. In other words, just because you have enough signal to produce stereo, doesn't mean you should if it comes with other artifacts such as high frequency scratching sounds.

A well designed receiver will be fully adaptive, deciding when to roll off the high frequencies to deal with multipath artifacts, when to blend in the channels more, and when to finally switch to mono or a combination of all of these techniques. More importantly, they will avoid making these switches abruptly as that can be almost as annoying.

Here are a bunch of references on work done in this area:

http://www.google.com/patents?id=GdgeAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q=&f=false
[Ford Motor Company: 1995]
"Control for an FM receiver reduces multipath distortion by reducing stereo separation and high frequency response in the demultiplexed signal. The receiver includes an FM detector including a noise detector as well as the signal strength meter for introducing control signals to a separation control and a frequency response control.... a stereo separation manager responds to a first threshold of noise and a frequency response manager responds to the second threshold. The frequency response control reduces the high frequency output at the stereo decoder or the audio processor. The respective managers introduce hysteresis by requiring a higher number of noise occurences above said thresholds to implement separation reduction, frequency response reduction, or a combination of the two. Thus excessive switching between levels of stereo separation and between levels of high frequency attenuation is avoided.

http://www.google.com/patents/about?id=P6EyAAAAEBAJ
"A stereophonic receiver includes internal separation control in which the sound separation is directly in accordance with noise reduction need and the amplitude and frequency of the sound signals monitored...."

http://www.google.com/patents/about?id=EHEpAAAAEBAJ
"An FM stereo decoding and separating circuit has an (AM) demodulator multiplier to which is connected the FM stereo composite signal and a signal of dominant frequency equal to and in phase (0.degree.) with respect to the pilot signal for retrieving the L-R signal from the composite signal....to the blend-control input for effecting the blending to a degree directly related to the amount of noise in a narrow band about the pilot in the composite signal."

http://www.google.com/patents/about?id=HXwiAAAAEBAJ
" noise control system for a FM stereo receiver senses the presence of noise outside of the FM stereo transmission bandwidth at an output of a FM detector and uses variations of amplitude of the sensed noise to control stereo channel separation and audio bandwidth control circuits of a stereo channel separation and audio bandwidth control circuits of a stereo decoder circuit of the stereo receiver."

I can keep going like this forever.

So please excuse me if I don't buy the fact that there is no car with fuel injection and variable valve timing :). Your statement would have been true 20 years ago but not now. FM radios today are quite sophisticated and much more pleasant to listen to than ones a decade or two back.

Of course that will affect stereo imaging.
All of the above factors will indeed impact stereo imaging. Switching to mono will obviously not be impacting the imaging but getting rid of it altogether.

Actually, it is exactly the same if you can reproduce both signals perfectly:

(L+R)+(L-R) = 2L
(L+R)-(L-R) = 2R

Divide the two numbers by 2 and you get L and R as if they were sent separately.

The result is L and R, but as I mentioned, these are derived from L+R and L-R, which is far different from having discrete L and R in the transmission chain. The L+R and L-R are not equal. The L+R is reasonably immune to interference and noise, but the L-R carried in the DSB subcarrier is not, especially when there is significant multipath. If the FM signal is strong and free of multipath, then the L-R can be quite clean and the resulting FM stereo performance can be quite good. If the signal quality is lower, the 19 kHz pilot tone may be weaker and more difficult to lock onto, the L-R could be weaker and noisier, and so the performance of the stereo decoder would change; it may blend less L-R into the matrix or even shut it off altogether. The quality of the L+R, though, is not likely to change as much.

If you were to broadcast the L on one FM carrier and the R on another, you'd probably find a much hardier set of performance characteristics--more like having discrete L and R--though the efficiency of the FM spectrum would be halved and our receivers would be a nightmare. You'd probably find similar results if the L+R and L-R were on separate carriers as well.

its on now friends and neighbors... :D

The result is L and R, but as I mentioned, these are derived from L+R and L-R, which is far different from having discrete L and R in the transmission chain. The L+R and L-R are not equal. The L+R is reasonably immune to interference and noise, but the L-R carried in the DSB subcarrier is not, especially when there is significant multipath. If the FM signal is strong and free of multipath, then the L-R can be quite clean and the resulting FM stereo performance can be quite good. If the signal quality is lower, the 19 kHz pilot tone may be weaker and more difficult to lock onto, the L-R could be weaker and noisier, and so the performance of the stereo decoder would change; it may blend less L-R into the matrix or even shut it off altogether. The quality of the L+R, though, is not likely to change as much.
All true. And beside the point. :) You seem to disagree with me saying there were multiple mitigation strategies for degradation of differential signals. In what way does any of the above address that? You seem to agree that there is degradation and then stop there.

If you were to broadcast the L on one FM carrier and the R on another, you'd probably find a much hardier set of performance characteristics--more like having discrete L and R--though the efficiency of the FM spectrum would be halved and our receivers would be a nightmare. You'd probably find similar results if the L+R and L-R were on separate carriers as well.
So? Who is discussing merits of different stereo modulation technologies? The discussion was whether people have heard adaptive stereo imaging in the car. I explained how this could exist. You seem to be saying it does not because we either live in stereo or mono based on strength of differential signal. I explained how that was yesterday's solution. If you agree, would be great to read that rather than what folks can go and find in any wikipedia description of FM stereo on their own :).

All true. And beside the point. :) You seem to disagree with me saying there were multiple mitigation strategies for degradation of differential signals. In what way does any of the above address that? You seem to agree that there is degradation and then stop there.


So? Who is discussing merits of different stereo modulation technologies? The discussion was whether people have heard adaptive stereo imaging in the car. I explained how this could exist. You seem to be saying it does not because we either live in stereo or mono based on strength of differential signal. I explained how that was yesterday's solution. If you agree, would be great to read that rather than what folks can go and find in any wikipedia description of FM stereo on their own :).

Your points about "adaptive stereo imaging" in car FM receivers are very good but I've not really noticed any difference from the old decoders of 30 years ago in fringe areas. Who has a critical ear when listening to analog FM in a car anyway. It's HD radio, music from the 200Gb hard-drive or other surround format on the 5.1 car surround system.

I have a ZFMSM Agile FM Stereo Modulator I use for in house audio. I'll connect an antenna and check the audio quality out in my car as I drive away.
http://www.starkelectronic.com/btc15-7.htm

You ask a hard question. Indeed, it was the same question I asked when I started the rat hole :). There are infinite scenarios for stereo imaging to change. Some of which will be audible to all, some will be audible to some, some will be audible to none! Just going through all of those scenarios in DBT will take a lifetime or more leaving us no time to actually go back and figure out how to justify them using measurements. I did say I picked a complex example to make a point, did I not? :D

BTW, have you ever driven around, listening to a weak FM station and noticing that stereo imaging changes, sometimes collapsing to mono and back?

Now you are trying to equate an FM signal strength issue which is handled differently than a stereo audio signal in a system?

And, that complex example, that is all that needs to be tested then. Any such test available? Most interested in that real test.

Now you are trying to equate an FM signal strength issue which is handled differently than a stereo audio signal in a system?
In what way is it "handled differently?" I explained how the stereo separation is varied in response to signal quality issues. So if you listen to FM radio in a later modern car, you are likely hearing varying levels of stereo imaging even though your speakers and their locations never change. In other words, I was hoping this would be a familiar example for people once they knew it was actually in play.

And, that complex example, that is all that needs to be tested then. Any such test available? Most interested in that real test.
What needs to be tested?

While searching for wav files to test car FM I found something closer to the subject of measuring audio imaging.

Experiments of Blind Source Separation from stereo recordings.
http://www.ism.ac.jp/~shiro/research/blindsep.html
http://www.irisa.fr/metiss/SASSEC07/SASSEC_ICA07.pdf
http://visl.technion.ac.il/demos/bss/
http://www.youtube.com/watch?v=dQwTn98rTuA

All true. And beside the point. :) You seem to disagree with me saying there were multiple mitigation strategies for degradation of differential signals. In what way does any of the above address that? You seem to agree that there is degradation and then stop there.

It is beside the point, but then you brought up up the issue in the first place.

So? Who is discussing merits of different stereo modulation technologies? The discussion was whether people have heard adaptive stereo imaging in the car. I explained how this could exist. You seem to be saying it does not because we either live in stereo or mono based on strength of differential signal. I explained how that was yesterday's solution. If you agree, would be great to read that rather than what folks can go and find in any wikipedia description of FM stereo on their own :).

Your reading comprehension is faulty, Amir. My point is that stereo imaging issues that arise in mobile FM reception are actually unique to that medium and do not occur in other stereo media that use discrete L and R channels. You seemed to imply that because stereo imaging can vary in FM reception in your car, we should be concerned about it in other stereo listening. If that's what you were trying to say, then you're comparing apples and dogs.

It is beside the point, but then you brought up up the issue in the first place.
Let me guess. Since I also used the word "radio" when I mentioned stereo imaging in FM radio, next you are going to copy and paste how AM radios work? :) There was nothing in my example that required talking about how FM radio modulates stereo channels. But rather, I wanted to see if people had heard how stereo separation in FM radio changes. If so, then they had a real life experience with meaning of "crosstalk" described earlier.

Your reading comprehension is faulty, Amir. My point is that stereo imaging issues that arise in mobile FM reception are actually unique to that medium and do not occur in other stereo media that use discrete L and R channels. You seemed to imply that because stereo imaging can vary in FM reception in your car, we should be concerned about it in other stereo listening. If that's what you were trying to say, then you're comparing apples and dogs.
You just made up a bunch of stuff about why I mentioned the example. Why not ask me what I meant by the example? In which case, I would have mentioned above.

If it is still not clear, FM radio is a system whereby modern implementations present you with a system whose level of channel crosstalk varies from 0 (mono) to ~40db (full stereo). If people have heard that, then they have a sense of what crosstalk means. Nothing was implied here whatsoever as to same cause affecting other reproduction system. Only that all audio devices have some level of crosstalk and if you want to get a feel for what crosstalk means in real life, listen to your FM radio. If you think this is an apples and dogs comparison, then I would say you are just being argumentative without adding anything to the conversation.

If you think this is an apples and dogs comparison, then I would say you are just being argumentative without adding anything to the conversation.

Look, we are all here to "argue" so please let's not state the obvious :). Everyone knows that already :D.

Well well, shoe's on the other foot eh :D

well well, shoe's on the other foot eh :d
:d