Jitter vs no-Jitter

[徐中銳]

Recalling some of Steve Nugent of Empirical Audio's piece on Jitter in Digital Audio Data Streams :

 

Recording Jitter

The recording of digital data is essentially a periodic sampling of a voltage (the voltage being the music waveform created from an instrument or microphone), where the period in theory is very precise. These captured sample voltages are then converted to digital data words and stored in memory or on recording media. There is no timing information actually stored in the data samples, but the timing is implicit in the samples themselves. There is however control information, which specifies the sample-frequency that should be used for playback, and other info such as pre-emphasis and word-length. If the timing that captured these data samples included jitter, then this is a characteristic of the samples and cannot be realistically eliminated during playback. This recording jitter is always there in the music file. Playback jitter is another matter however.

 

Playback Jitter Contributions

Playback jitter originates from a large number of contributors, which are usually additive. These range from the master clock, which has its own jitter, to logic devices, to mechanical systems for spinning a CD. One digital cable can even add more jitter than another. Each contributor adds more jitter to the signal as it makes its way to the D/A converter. This summation of this jitter is the system jitter.

 

Here is a lengthy, but probably not complete list of jitter contributors, including how each of these can or might add jitter to a digital audio system:

1. Master Clock Jitter

This is the source clock for...

I trust interested readers will fully...

[barrows]

The article linked below reads like any audiophile investigation into the sound of audio components. Sighted differences disappearing when blind tested, and Lord Rayleigh's famous words " What we cannot measure, we do not know". He also uses many of the same tools used in our familiar fields of audio analysis, and asks many of the same questions.

 

Flute Tone Investigations - Intro

 

Edit: The link to Gregor Widholm's paper in the above intro is broken. This works:

 

Wall material and the sound of the flute - Institute of Music Acoustics (Wiener Klangstil)

 

Hahaha! "Sighted differences disappearing when blind tested", yes, this is a well known problem amongst experienced listeners and testers, hence the conclusion that blinded testing is invalid for evaluating audio playback systems for sonic performance.

[lateboomer]

I and my brother together think A2 is the one with less jitter. We think A2 has better depth, quieter background and better instrument separation. So we voted A2 in another forum. Of course we might be wrong and fall flat on our face.

[bibo01]

Thanks to both of you.

[bit01]

I find A2 musically to sound 'better' (clearer/better defined flow) and therefore assume it has the less jitter!

[bibo01]

I find A2 musically to sound 'better' (clearer/better defined flow) and therefore assume it has the less jitter!

 

Thanks for your vote

[bit01]

Thanks for your vote

 

thx 2u4 the poll - should be quite educational

[mmerrill99]

The article linked below reads like any audiophile investigation into the sound of audio components. Sighted differences disappearing when blind tested, and Lord Rayleigh's famous words " What we cannot measure, we do not know". He also uses many of the same tools used in our familiar fields of audio analysis, and asks many of the same questions.

 

Flute Tone Investigations - Intro

 

Edit: The link to Gregor Widholm's paper in the above intro is broken. This works:

 

Wall material and the sound of the flute - Institute of Music Acoustics (Wiener Klangstil)

 

Yes what would you expect from the pseudo-scientific investigations contained in the above articles, only the same results as all other pseudo-scientific investigations conducted in audio - "There are no differences".?

[Sal1950]

Yes what would you expect from the pseudo-scientific investigations contained in the above articles, only the same results as all other pseudo-scientific investigations conducted in audio - "There are no differences".?

 

Read Lie #4

The Ten Biggest Lies in Audio - ecoustics.com

[mmerrill99]

Read Lie #4

The Ten Biggest Lies in Audio - ecoustics.com

 

Yes, read it before & when it comes to this quote " and of course assorted psychobabble on the subject of aural perception. None of that amounts to anything more than a red herring, of one flavor or another, to divert attention from the basics of controlled testing." it shows just how pseudo-scientific the writer & your quoting of him reveals.

 

So, let's see what you nominate are the criteria necessary for a rigorous, scientifically valid ABX test & we will judge whether you are scientific or pseudo-scientific?

[bibo01]

Yes, read it before & when it comes to this quote " and of course assorted psychobabble on the subject of aural perception. None of that amounts to anything more than a red herring, of one flavor or another, to divert attention from the basics of controlled testing." it shows just how pseudo-scientific the writer & your quoting of him reveals.

 

So, let's see what you nominate are the criteria necessary for a rigorous, scientifically valid ABX test & we will judge whether you are scientific or pseudo-scientific?

A well defined protocol exists for "Subjective assessment of sound quality – A guide to existing Recommendations" - ITU-R BS.1283.

 

Please read:

http://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1283-1-200312-I!!PDF-E.pdf

 

Furthermore, confidence interval is a statistical analysis tool. Look it up. It simply provides more information and allows better analysis of small samples than the ABX crowds .05 significance level.

[mmerrill99]

Yes, I know the standard & wondered if Sal1950 would know about this standard & stand by these recommendations - would he realize that forum run blind tests & the sort of blind tests nominate in the article he linked to are pseudo-science?

A well defined protocol exists for "Subjective assessment of sound quality – A guide to existing Recommendations" - ITU-R BS.1283.

 

Please read:

http://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1283-1-200312-I!!PDF-E.pdf

 

Furthermore, confidence interval is a statistical analysis tool. Look it up. It simply provides more information and allows better analysis of small samples than the ABX crowds .05 significance level.

[4est]

It is hard to teach to those who preach!

Yes, I know the standard & wondered if Sal1950 would know about this standard & stand by these recommendations - would he realize that forum run blind tests & the sort of blind tests nominate in the article he linked to are pseudo-science?

[mmerrill99]

It is hard to teach to those who preach!

Yes it appears that anybody who uses the phrase "controlled testing" &/or DBT think that they are on the side of science & science is backing them - nothing could be further from the truth - it's the epitome of irony.

[Sal1950]

Yes it appears that anybody who uses the phrase "controlled testing" &/or DBT think that they are on the side of science & science is backing them

 

We are, do you call "it sounds good to me" science? LOL

Peter laid out all you need to know to run reasonably valid tests

But drink the KoolAid and enjoy your cult approach.

[4est]

Do you mean as opposed to your "I've got all the answers." bullying tactics?

But drink the KoolAid and enjoy your cult approach.

[Jud]

We are, do you call "it sounds good to me" science? LOL

Peter laid out all you need to know to run reasonably valid tests

But drink the KoolAid and enjoy your cult approach.

 

Wondering to what extent you're serious in mocking ITU standards and peer reviewed science, and to what extent you're just trying to stir up discussion/controversy.

[mmerrill99]

We are, do you call "it sounds good to me" science? LOL

Peter laid out all you need to know to run reasonably valid tests

But drink the KoolAid and enjoy your cult approach.

Interesting that you reject real science which imposes some rigour in favour of your belief system & you accuse me of a "cult approach". The lack of self knowledge displayed is only surpassed by the irony of your statements.

[jabbr]

Thanks for taking the time and effort to set this up -- I look forward to the results. Let's everyone remember that this is a discussion forum for audiophiles and not an NSF grant review committee:)

[Jud]

Thanks for taking the time and effort to set this up -- I look forward to the results. Let's everyone remember that this is a discussion forum for audiophiles and not an NSF grant review committee:)

 

If there was a grant in it, he might be willing to undergo the review.

[bibo01]

I declare the poll closed.

 

Password to open file "Nuovo documento di testo", included with the two tracks used for the poll, with solution is:

jdnfiudyt8o547ty5o8ejthelibgh8gh

 

At the moment of closure the poll result is:

 

Track "A1" = 6

Track "A2" = 7

I am not sure to hear differences = 2

 

We are taking into account that two users mistakenly voted A2, instead of A1.

[esldude]

I declare the poll closed.

 

Password to open file "Nuovo documento di testo", included with the two tracks used for the poll, with solution is:

jdnfiudyt8o547ty5o8ejthelibgh8gh

 

At the moment of closure the poll result is:

 

Track "A1" = 6

Track "A2" = 7

I am not sure to hear differences = 2

 

We are taking into account that two users mistakenly voted A2, instead of A1.

 

So for the six or seven who chose correctly which was no jitter, what is the prize they win?

[bibo01]

So for the six or seven who chose correctly which was no jitter, what is the prize they win?

 

The broken "jittered" sound card

[bibo01]

I thank Tom "Gefrusti" for his indispensable help to the poll

 

-----------------------

I was not aware of the solution before the poll.

As reported from the file I mentioned above, the solution is:

 

DAC A1 = jitter OFF.

 

DAC A2 = jitter On

 

-----------------------

 

What is interesting in my view is that the difference, which everyone was aware of before the test, was not at all easy to spot.

The majority of the voters preferred the "jittered" track.

In the Italian forum NextHardware where I was running the same poll, I also voted A2

[Sal1950]

Wondering to what extent you're serious in mocking ITU standards and peer reviewed science, and to what extent you're just trying to stir up discussion/controversy.

 

I find it interesting and curious that whenever I post something like this ya'll have to reply with mis-quotes and outright lies that the truth of which is obvious to anyone that read the thread. I neither "mocked ITU standards" nor "rejected what you believe to be real science"

I simply said I find the test criteria laid down by Peter Aczel sufficient IMHO.

So if your going to reply to me use truthful quotes of my statements.

In any case we all know that the position of the subjectives here is that ALL ABX-DBT tests are unreliable and only your golden ears can be counted on to reveal the truth, just as long as your opinions never have to be put to any controled tests

 

bibo01, Thanks for all the hard work and time you invested in putting this test together!