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ABX testing vs. unconscious perception/decision, enjoyment, and so on, Split from “xiphmont—‘There is no point to 24/192’”/TID:93853 (TOS #5)
icstm
post Mar 19 2012, 12:59
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BACK TO MY OP
How does THIS page change things?
It is from The American Physiological Society Journal of Neurophysiology.

It is 10 years old, so there maybe some newer studies.
It shows that the brain can responde to high-frequency components (HFCs) above the audible range, but I would want to know what impact this has on our conscious states.
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greynol
post Mar 19 2012, 13:03
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A search of the forum should have revealed that the topic has already been discussed. As such I don't see the need to have it here as well.

This post has been edited by greynol: Mar 19 2012, 13:08


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icstm
post Mar 19 2012, 14:55
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ah, did not realise that it was the much discredited work that I have seen referenced in other treads. Thanks for pointing out.

Has anyone else tried to replicate in terms of using EEG and PET scans? It seems sensible. It would be great if this has been done and the results are negative.

EDIT: further reading the old threads here it makes me wonder why this discussion in general has not be closed down? Is it for the reasons of my evolution analogy, ie there is evidence (allbeit incomplete) that there is NO difference when listening to this 24/192 recordings, however, even though there is no real evidence to support their position, because there is no evidence irrefutably prove that there is no difference they carry on?

For me I would ideally like to see something along the lines of a set of EEG or PET scans.
I saw some great scans that were taken whilst musicians were playing known pieces of music vs inprov and showed different parts of the brain at work - so I am sure they should be able to find a difference if there was one for our purposes.

This post has been edited by icstm: Mar 19 2012, 15:03
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DonP
post Mar 19 2012, 15:09
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QUOTE (icstm @ Mar 19 2012, 09:55) *
Has anyone else tried to replicate in terms of using EEG and PET scans? It seems sensible. It would be great if this has been done and the results are negative.


If the argument is that the process of ABX test is too distracting, I doubt a PET scan will fly.
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icstm
post Mar 19 2012, 16:09
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yeah, I was thinking about that too. Plus they are quite noisey machines...

So what can we do? I need some sort of remote analysis! smile.gif
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Arnold B. Kruege...
post Mar 19 2012, 16:56
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QUOTE (splice @ Mar 18 2012, 19:17) *
QUOTE (googlebot @ Mar 18 2012, 06:40) *
... the clock rate must still be reconstructed from the S/PDIF input signal, and is thus prone to jitter. ...


Er... not directly. The output clock is derived from the state of the FIFO buffer. It does vary slowly, but short-order intersample variations on the clock derived from the input S/PDIF signal are effectively suppressed. Consider the FIFO as a low-pass "jitter filter" with a cutoff frequency set by the size of the FIFO.


Agreed.

This technology has to work, because the above methodology how every CD player contend with the often egregiously jittery digital data that comes off of the CD itself. Nothing new, either. I first saw this method work on IBM computer tape drives in the 1960s, and it was old technology then!
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Porcus
post Mar 19 2012, 19:04
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QUOTE (Arnold B. Krueger @ Mar 19 2012, 16:56) *
QUOTE (splice @ Mar 18 2012, 19:17) *
QUOTE (googlebot @ Mar 18 2012, 06:40) *
... the clock rate must still be reconstructed from the S/PDIF input signal, and is thus prone to jitter. ...


Er... not directly. The output clock is derived from the state of the FIFO buffer. It does vary slowly, but short-order intersample variations on the clock derived from the input S/PDIF signal are effectively suppressed. Consider the FIFO as a low-pass "jitter filter" with a cutoff frequency set by the size of the FIFO.


Agreed.

This technology has to work, because the above methodology how every CD player contend with the often egregiously jittery digital data that comes off of the CD itself.


While I have always assumed buffers to 'work' much in the sense that keeping the buffer roughly half-full, allows the next stage time to adjust slowly yet timely (which I have guessed is precisely what we want), I still don't really know what could go 'wrong' about this. In principle, it could run overfull and cropping off a sample, which would probably be less audible than running empty. But how would these issues sound on the borderline between total failure (i.e. no bits to wait for) and barely running? Could the 'scratch-scratch-schz-schz' type sound from badly damaged CDs be it?

(I guess somebody will jump the chance to say that such a question merely illustrates the that the problem is bogus ...)


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googlebot
post Mar 19 2012, 20:04
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QUOTE (splice @ Mar 19 2012, 00:17) *
Er... not directly. The output clock is derived from the state of the FIFO buffer. It does vary slowly, but short-order intersample variations on the clock derived from the input S/PDIF signal are effectively suppressed. Consider the FIFO as a low-pass "jitter filter" with a cutoff frequency set by the size of the FIFO.


Sounds nice, but the clock is usually recovered by a phase locked loop. When you feed this directly into an common DAC you can still measure slight amounts of jitter at the output. Reclocking is usually only found in rather expensive or exotic audio gear.

You can get rid of the jitter completely if you just save the buffer's output to your hard disk and play it back later at a fixed rate, e. g. at 44.1kHz (you could call that manual reclocking). The buffer mechanism you describe has nothing to do with clock recovery. The FIFO is not emptied in a constant rate, but in bursts, no clock signal is recovered at this stage. And refill speed is determined the PLL recovered input clock. You can also get rid of the input jitter by letting your sound card push samples at the PLL derived rate into a memory buffer and then empty the buffer at a chosen output sample rate.* And that's indeed possible, but not what is usually happening, neither in regular playback hardware nor software, in contrast to what your simplification suggests.

I'm not claiming that this is relevant in terms of audibility. But arguing from an objectivist perspective has enough credible aspects already (e. g. demanding double blind proof). IMHO you don't support the cause by denying inaudible, but measurable, imperfections of common playback paths with oversimplification.

* Using the PLL recovered clock as you master guarantees zero data loss due to clock differences (no clock is perfect). Pulling at a fixed rate will loose data here and then, again probably inaudible most of the time, but still a property one usually does not want in a digital system.

This post has been edited by googlebot: Mar 19 2012, 20:35
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Arnold B. Kruege...
post Mar 20 2012, 14:38
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QUOTE (googlebot @ Mar 19 2012, 15:04) *
QUOTE (splice @ Mar 19 2012, 00:17) *
Er... not directly. The output clock is derived from the state of the FIFO buffer. It does vary slowly, but short-order intersample variations on the clock derived from the input S/PDIF signal are effectively suppressed. Consider the FIFO as a low-pass "jitter filter" with a cutoff frequency set by the size of the FIFO.


Sounds nice, but the clock is usually recovered by a phase locked loop.

When you feed this directly into an common DAC you can still measure slight amounts of jitter at the output. Reclocking is usually only found in rather expensive or exotic audio gear.


According to the manufacturer's data sheet the TI PCM2707 USB DAC chip includes a PLL and a FIFO buffer.

TI PCM 2707 data sheet

Fully assembled USB DACs incorporating this chip sell on eBay for under $70.

EBay offering

I don't think this is an exceptional part, but similar to competitive parts from other sources.
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icstm
post Mar 20 2012, 16:48
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A PLL is to sync to signals to the same clock, whereas a FIFO buffer is a buffer - why wouldn't you have both?
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pdq
post Mar 20 2012, 17:37
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The amount of filtering that you can apply to the PLL is proportional to the amount of buffering that you provide. There is no reason that the PLL filter can't be fast enough that zero buffering is needed, but obviously this affects the amount of input jitter that can be tolerated, as well as the amount of output jitter.
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Arnold B. Kruege...
post Mar 20 2012, 18:09
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QUOTE (icstm @ Mar 16 2012, 07:31) *
SOME THOUGHTS

All this talk about skin “hearing” music, “feeling” the vibrations of the music etc raises for me a separate debate.

Whilst I completely agree that ABX is an excellent tool for spotting consciously detectable differences (ie respondents must be wilfully aware of the difference to make their choice) what about our unconscious decisioning? Just the other day their was a BBC documentary “out of control” which they were explaining how your unconscious mind is often calling the shots and influencing the decisions you make.

So we have 3 different types of tests:
1) Signal waveform analysis (as was used to check to see if JPlay was doing anything or FLAC v WAV using Audio DiffMaker
2) ABX audio testing (man in the middle) for checking for conscious discrimination of different samples
3) Enjoyment factor (or some other form of what some philosophers call qualia)


In really long-term ABX tests, several of us have noticed that we tend to forget that we are doing an ABX test, and then remember it. The wake up call to self from self goes something like this:

Oh, by the way you are supposed to be doing an ABX test, and the display says X so are we still having fun?

How remote from the actual sensing part of the evaluation do we have to get before we can believe that our sensing adequately engaged our unconscious thoughts?
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icstm
post Mar 22 2012, 12:36
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If you are forgetting that you are doing an ABX, then I think you are basically there! But how often does that happen?

I would have thought to do an ABX you would need to be listening to the same track in the same room, so when you say long-term, how do you accomplish it?
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greynol
post Mar 22 2012, 14:31
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http://www.hydrogenaudio.org/forums/index....st&p=789697

...rinse and repeat(?).


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icstm
post Mar 22 2012, 17:04
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@greynol
You've lost me there, Arnold was providing an example where people had forgotten they were doing an ABX test. Drewfix's post simply misses the fact that doing something under "test" conditions is different from other conditions. What Arnold's example seems to suggest is where someone had got to the point where they forgot they were in test conditions.

It is a bit like an unatural interview improving once the subject forgets the camera is there.
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greynol
post Mar 22 2012, 17:59
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I guess I'd like to see you answer drewfx's point and points of others who I believe rightly suggest that distinguishing differences requires critical listening over casual listening rather than dismiss them.


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drewfx
post Mar 22 2012, 18:05
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QUOTE (icstm @ Mar 22 2012, 11:04) *
Drewfix's post simply misses the fact that doing something under "test" conditions is different from other conditions.


There's a difference between saying that there are things we perceive unconsciously/subconsciously and asserting that those things can only be perceived unconsciously/subconsciously.

If you're driving down the street you might not consciously notice a red car with the windows rolled down parked on the left (along with a lot of other stuff), but that doesn't mean you couldn't see it if you were looking for it.

The question I'm asking is whether there is any evidence that there are "audible" things that are real and not imagined and can only be noticed unconsciously/subconsciously and/or outside of ABX testing?

Or are we discussing a theoretical possibility that such things could possibly exist and thus should be tested for?
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greynol
post Mar 22 2012, 18:23
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To take this further, someone investing time and/or money towards this endeavor will only likely do so if you adequately address drewfx's first question. If you can only say yes to drewfx's second question then I think you're out of luck.

This post has been edited by greynol: Mar 22 2012, 18:49


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Arnold B. Kruege...
post Mar 23 2012, 00:08
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QUOTE (icstm @ Mar 22 2012, 07:36) *
If you are forgetting that you are doing an ABX, then I think you are basically there! But how often does that happen?


YMMV

QUOTE
I would have thought to do an ABX you would need to be listening to the same track in the same room, so when you say long-term, how do you accomplish it?


Nothing special. Just leave the equipment hooked up and powered up and use it normally. The hardware ABX box had a battery backup for its memory so that if you lost power during a long-term ABX, you could just restart the same test when the power came back.
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Arnold B. Kruege...
post Mar 23 2012, 00:12
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QUOTE (greynol @ Mar 22 2012, 12:59) *
I guess I'd like to see you answer drewfx's point and points of others who I believe rightly suggest that distinguishing differences requires critical listening over casual listening rather than dismiss them.


I'd like to see Drewfx answer the following question, which I think needs to be answered before his.

How do you reliably know that you unconsciously perceive something that you are not conscious of during the test, and possibly never conscious of?
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dhromed
post Mar 23 2012, 00:46
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QUOTE (Arnold B. Krueger @ Mar 23 2012, 00:12) *
How do you reliably know that you unconsciously perceive something that you are not conscious of during the test, and possibly never conscious of?

Is that question mostly rhetorical?
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greynol
post Mar 23 2012, 01:26
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Here we go again with the flying spaghetti monster.

This post has been edited by greynol: Mar 23 2012, 06:26


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drewfx
post Mar 23 2012, 02:06
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QUOTE (Arnold B. Krueger @ Mar 22 2012, 18:12) *
I'd like to see Drewfx answer the following question, which I think needs to be answered before his.

How do you reliably know that you unconsciously perceive something that you are not conscious of during the test, and possibly never conscious of?


I'll be happy to answer that:

My answer is that I don't know, and I don't particularly care about stuff I can't consciously perceive until someone shows me a good reason why I should. smile.gif I tend to care more about stuff I can actually consciously perceive. YMMV
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greynol
post Mar 23 2012, 06:03
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Because of my masochistic tendencies, I had to go back over and look at the title that was provided to the topic after it was most certainly going to derail a topic that was deserving of better and zeroed in on the word happiness which prompted me to search for the thread where some people wouldn't accept that fact that ABX tests do not have to have time limits.

http://www.hydrogenaudio.org/forums/index....showtopic=38041

Spoiler alert: there is nothing in this discussion that can't also be found there.

This post has been edited by greynol: Mar 23 2012, 06:04


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2Bdecided
post Mar 23 2012, 10:30
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QUOTE (greynol @ Mar 23 2012, 05:03) *
Spoiler alert: there is nothing in this discussion that can't also be found there.
So true. So often. Maybe we need to get out more? Or stop trying to fix the world one audiophile at a time? wink.gif

Cheers,
David.

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