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Topic: Audibility of "typical" Digital Filters in a Hi-Fi Playback  (Read 312973 times) previous topic - next topic
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Audibility of "typical" Digital Filters in a Hi-Fi Playback

It's being touted as such on some other forums.  A paper to be presented this month by Meridian at the AES Convention in LA.

(NB it has been posted once before on HA  in the midst of a thread...but perhaps we can use this thread to discuss it, once it is available)


http://www.aes.org/events/137/papers/?ID=4058
Quote
P14-3 The Audibility of Typical Digital Audio Filters in a High-Fidelity Playback System—Helen M. Jackson, Meridian Audio Ltd. - Huntingdon, UK; Michael D. Capp, Meridian Audio Ltd. - Huntingdon, UK; J. Robert Stuart, Meridian Audio Ltd. - Huntingdon, UK
This paper describes listening tests investigating the audibility of various filters applied in high-resolution wideband digital playback systems. Discrimination between filtered and unfiltered signals was compared directly in the same subjects using a double-blind psychophysical test. Filter responses tested were representative of anti-alias filters used in A/D (analog-to-digital) converters or mastering processes. Further tests probed the audibility of 16-bit quantization with or without a rectangular dither. Results suggest that listeners are sensitive to the small signal alterations introduced by these filters and quantization. Two main conclusions are offered: first, there exist audible signals that cannot be encoded transparently by a standard CD; and second, an audio chain used for such experiments must be capable of high-fidelity reproduction.
Convention Paper 9174

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #1
I recall reading over some of their previous information regarding listeners favoring the filters that Meridian was using against several others. I'm quite appreciative of them for share their findings with the audio community. It will be interesting to revisit that topic to see if Meridian has come to new conclusions. Thank you for posting this.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #2
It's being touted as such on some other forums.  A paper to be presented this month by Meridian at the AES Convention in LA.

(NB it has been posted once before on HA  in the midst of a thread...but perhaps we can use this thread to discuss it, once it is available)


http://www.aes.org/events/137/papers/?ID=4058
Quote
P14-3 The Audibility of Typical Digital Audio Filters in a High-Fidelity Playback System—Helen M. Jackson, Meridian Audio Ltd. - Huntingdon, UK; Michael D. Capp, Meridian Audio Ltd. - Huntingdon, UK; J. Robert Stuart, Meridian Audio Ltd. - Huntingdon, UK
This paper describes listening tests investigating the audibility of various filters applied in high-resolution wideband digital playback systems. Discrimination between filtered and unfiltered signals was compared directly in the same subjects using a double-blind psychophysical test. Filter responses tested were representative of anti-alias filters used in A/D (analog-to-digital) converters or mastering processes. Further tests probed the audibility of 16-bit quantization with or without a rectangular dither. Results suggest that listeners are sensitive to the small signal alterations introduced by these filters and quantization. Two main conclusions are offered: first, there exist audible signals that cannot be encoded transparently by a standard CD; and second, an audio chain used for such experiments must be capable of high-fidelity reproduction.
Convention Paper 9174



I'm expecting yet another trip through the land of testmanship.

First person to post a link to the preprint wins!

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #3
this is just a shocking bit of sophistry and rhetorical sleight-of-hand, even from Amir. He's now claiming (without quite saying it outright) that M&M 2007 wasn't peer reviewed.  His evidence is....


http://www.avsforum.com/forum/91-audio-the...ml#post28499689

Quote
Yes, the Journal has "scholarly" papers in it. But no, just because something is in the Journal, it does NOT mean it is a scholarly "peer reviewed paper." The proof is actually in the link you provided. Before we look at that, let's see how AES itself describes the journal it publishes: http://www.aes.org/journal/

The Journal contains state-of-the-art technical papers and engineering reports; feature articles covering timely topics; pre and post reports of AES conventions and other society activities; news from AES sections around the world; Standards and Education Committee work; membership news, patents, new products, and newsworthy developments in the field of audio.

As you see, "state-of-the-art technical papers" is only one of the items in the journal. Those papers are indeed selected to be scholarly and properly reviewed to make sure the writer knows the audio theory and science before acceptance. Such is the Bob Stuart paper which is some 20-30 pages long, is full of audio theory and analysis.

The Meyer and Moran is the second type I have highlighted in red: Engineering Report. How do we know that? It says right on top in the link you provided!

Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback

[Engineering Report] Claims both published and anecdotal are regularly made for audibly superior sound quality

The write-up says exactly the same thing on top of the title page so that there is no confusion whatsoever that what is about to come is not a scholarly paper. It is a report on "engineering" work done which in this case is a listening test. The "peer" review that was performed on it was likely the fact that it was not a sighted test. Outside of that, there is no discussion of theory or science in the write-up to have been "peer reviewed." And for sure, nobody in AES verified the core content of the write-up: the listening test. All the work was taken at face value and published. Only the organizers of the work are accountable for its accuracy, not the AES.

I realize understanding the nature of the Journal is beyond what is expected from people not in the audio research/industry. So mistaking their work for a peer reviewed paper is understandable. What is not understandable is why after I explain what it is, you chime in to still on saying otherwise. Hopefully this more detailed explanation puts posts like yours behind us and from here on, we don't exaggerate or misstate the nature of audio work in front of us.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #4
No scientific journal tries to reproduce the result of a paper before it is published. A "peer reviewed" paper is pre-screened by experts in the field for obvious errors, but it has never been my experience that they attempt actual verification of the results either. The real verification is performed after publication when others either corroborate or refute the original paper, and then publish their own evidence.

I think that having seven years elapse without anyone, AFAIK, presenting strong evidence to contradict M&M is in itself a corroboration.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #5
It's just striking that this

"The Journal contains state-of-the-art technical papers and engineering reports; "

would be boldly interpreted to mean 'technical papers are peer reviewed, but engineering reports are not'.

And of course no one ever claimed that every article, news item, letter, etc in JAES is peer reviewed.  That's no more true in JAES than it is in, say, Nature or Science.

It's possible, but not  obvious from anything Amir has quoted,  that 'engineering reports' are not reviewed, while  'technical papers' are (or even vice versa) .  The thing to do, of course, is to consult the JAES instructions to authors (which requires a login), or an editor at the journal, to see what sorts of articles are peer-reviewed or not. Amir appears not to have done that.



Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #6
No scientific journal tries to reproduce the result of a paper before it is published. A "peer reviewed" paper is pre-screened by experts in the field for obvious errors, but it has never been my experience that they attempt actual verification of the results either.


Actually, I've done exactly that when the paper is from someone credible but the claimed results are suspicious.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #7
It's just striking that this  "The Journal contains state-of-the-art technical papers and engineering reports; "  would be boldly interpreted to mean 'technical papers are peer reviewed, but engineering reports are not'.  And of course no one ever claimed that every article, news item, letter, etc in JAES is peer reviewed.  That's no more true in JAES than it is in, say, Nature or Science.  It's possible, but not  obvious from anything Amir has quoted,  that 'engineering reports' are not reviewed, while  'technical papers' are (or even vice versa) .  The thing to do, of course, is to consult the JAES instructions to authors (which requires a login), or an editor at the journal, to see what sorts of articles are peer-reviewed or not. Amir appears not to have done that.


It seems pretty clear to me "Engineering Reports" comes under the banner of, or is a subset of "All submissions", and therefore are by definition peer reviewed:


"JAES Publication Policy
The AES Journal seeks original unpublished research papers and engineering reports of archive quality on subjects related to the audio domain. All submissions will go through a peer review process to check their suitability for JAES."

http://www.aes.org/journal/authors/guidelines/

Convention papers, such as that new Meridian thing, aren't [necessarily] "peer reviewed" nor are they "published in the Journal as a paper", however they may be submitted at a later *date* to be published. [And I don't know if Meridian has submitted their thing] At least that's how I understand it.

More distinctions here:

http://www.aes.org/journal/authors/manuscript_types/

P.S. I typically ignore that troll in that other forum but anyone wishing to use any of this, by all means do so, and no need to reference me. [Also keep in mind he's quite likely reading all of this.]

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #8
Nice work. Seems pretty normal to me:  experimental papers/reports go through peer review.  Even letters to the editor (responding to a published article) are at least 'reviewed' by the author of the original article.


Amir's take on peer-reviewed scientific publication is so bizarre that I have to wonder if he has ever authored one.



Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #9
Nice work.


Agreed.

Quote
(his) take on peer-reviewed scientific publication is so bizarre that I have to wonder if he has ever authored one.


IME you've set the bar too high. I'd put the bar at" "Read one and really understood it".

I will represent myself as someone who has for the last 3 years struggled mano-a-mano with that man as much as anybody, if not more. 

His mental state and behavior are fairly predictable to me. No way does it seem to me to involve what most of us consider to be accurate perceptions.

I might add there are some who will say the same about me! ;-)  One is no doubt JA.  I'm am quite pleased with that.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #10
I will represent myself as someone who has for the last 3 years struggled mano-a-mano with that man as much as anybody, if not more.    His mental state and behavior are fairly predictable to me. No way does it seem to me to involve what most of us consider to be accurate perceptions.
  He's now posting his own screen capture of a Meridian white paper image in the related High-Res Audio Panels at AES 2014 thread, from his private smugmug photo account, showing the threshold of human hearing superimposed over the noise floor of 16 bit audio, without (of course) the advantages of noise shaping since it betrays his/Meridians agenda and CLAIMS it also appears in this JAES paper, perhaps attempting to give it more street cred than the corporate ad he actually took it from:

http://www.aes.org/e-lib/browse.cfm?elib=7140

I don't doubt its legitimacy but I can't currently substantiate his SOURCE claim without buying the paper, (and I'm cheap  )  so I'm asking for help Arny, since you seem to have battled him on the origins of his version of the Meridian image before. Can you verify it truly exists in the JAES paper he claims it also appears in?

Also, if you don't come back to help counter this commercial troll/ high-end audio lobbyist, I think I may have to throw in the towel myself. As Princess Leia once said: "Please come back, Obiwan K'. Arny; you're our only hope!"

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #11
I will represent myself as someone who has for the last 3 years struggled mano-a-mano with that man as much as anybody, if not more.    His mental state and behavior are fairly predictable to me. No way does it seem to me to involve what most of us consider to be accurate perceptions.
  He's now posting his own screen capture of a Meridian white paper image in the related High-Res Audio Panels at AES 2014 thread, from his private smugmug photo account, showing the threshold of human hearing superimposed over the noise floor of 16 bit audio, without (of course) the advantages of noise shaping since it betrays his/Meridians agenda and CLAIMS it also appears in this JAES paper, perhaps attempting to give it more street cred than the corporate ad he actually took it from:

http://www.aes.org/e-lib/browse.cfm?elib=7140

I don't doubt its legitimacy but I can't currently substantiate his SOURCE claim without buying the paper, (and I'm cheap  )  so I'm asking for help Arny, since you seem to have battled him on the origins of his version of the Meridian image before. Can you verify it truly exists in the JAES paper he claims it also appears in?

Also, if you don't come back to help counter this commercial troll/ high-end audio lobbyist, I think I may have to throw in the towel myself. As Princess Leia once said: "Please come back, Obiwan K'. Arny; you're our only hope!"



I don't have any access to the recent AES paper in question that you don't have. My usual sources of such PDFs have grown quiet.

However, superpositions of the threshold of hearing and the 16 bit noise floor are old news.  The 1997 Stuart he quotes from here http://www.avsforum.com/forum/91-audio-the...ml#post28510553  are flawed by the fact that Stuart ignores noise shaping even though Meridian has proudly sold devices that implement noise shaping since no later than the early 1990s.

I think a PDF of some version of the 1997 paper is on the Meridian web site.

What can one say about someone who ignores his own products when they would destroy his agenda?

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #12
I don't doubt its legitimacy but I can't currently substantiate his SOURCE claim without buying the paper, (and I'm cheap  )  so I'm asking for help Arny, since you seem to have battled him on the origins of his version of the Meridian image before. Can you verify it truly exists in the JAES paper he claims it also appears in?
I think Amir quoted from an old paper "Coding High Quality Digital Audio" that is available on the Meridian website
Quote
This previously unpublished paper is a more complete version of the article published by Audio Magazine in March 1998. This paper was in turn a subset of the landmark paper 'Coding Methods for High-Resolution Recording Systems' presented at AES, New York in 1997 - copies of which can be obtained from AES as preprint #4639
[/size]

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #13
Stuart;s paper was an AES Convention Paper in 1997,  then an Audio magazine article in 1998,  then a JAES Paper in 2004. There is no reason to question its legitimacy on that score.

The white paper (referencing no papers later than 1997)  on Meridian's site is another incarnation.  Its provenance is explained there

Quote
Coding High Quality Digital Audio by Bob Stuart. This previously unpublished paper is a more complete version of the article published by Audio Magazine in March 1998. This paper was in turn a subset of the landmark paper 'Coding Methods for High-Resolution Recording Systems' presented at AES, New York in 1997 - copies of which can be obtained from AES as preprint #4639


As I said, he's been flogging this for a long time.

Meyer and Moran's 2007 paper was a direct response to the 2004 JAES paper, and was preceded by a critical letter to the editor or JAES, published in December 2004,  signed by David Moran, Roy Allison, and E. Brad Meyer. 


Amir may think some of us don't know this history, but we do.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #14
Amir may think some of us don't know this history, but we do.


Just glanced at the thread and it appears my BFF "likes" the Dunning-Kruger gangs rejection of DBT
Quote
Other critical issues include fundamental flaws in DBT itself as a test method


Which makes sense given Bluescreen mans own methods for demonstrating the disorder.
It seems those stricken are ok touting papers....using a method they reject.

cheers,

AJ
Loudspeaker manufacturer

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #15
It seems pretty clear to me "Engineering Reports" comes under the banner of, or is a subset of "All submissions", and therefore are by definition peer reviewed:  "JAES Publication Policy The AES Journal seeks original unpublished research papers and engineering reports of archive quality on subjects related to the audio domain. All submissions will go through a peer review process to check their suitability for JAES."  http://www.aes.org/journal/authors/guidelines/


Plus here is Moran himself stating it was peer reviewed:

"We got pretty heavily peer-reviewed, actually, compared with other AESJ papers I have been involved with.

I notice no one here objects to the totally untested, unsubstantiated adulatory characterization of hi-rez that licensor Bob Stuart published in the AESJ. Which is what got us motivated to do the test.

If you feel our result is disprovable ("wrong") and that hi-rez is audibly better in some way, well, do your own proper test."

-- David Moran http://www.audioasylum.com/cgi/t.mpl?f=prophead&m=37062

Is it possible any actual test of audibility is, by definition an "engineering report" and research papers are more of the self congratulatory sort of papers of Meridian's Stuart, where he pontificates about WHY his $20,000 SACD machine sounds so great must be due to X, Y, and Z?


It would make sense to me to make some differentiation between papers which are "test results of humans"  vs. "guessing what they must hear", right?

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #16
On a different note, how long until this conference paper gets added to the AES' online archive? Will it come with the October issue of the journal?

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #17
On a different note, how long until this conference paper gets added to the AES' online archive?


IME, varies

Quote
Will it come with the October issue of the journal?


Unlikely, but probably never.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #18
The Stuart AES Convention paper is now available for purchase/download at the AES library


Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #19
The Stuart AES Convention paper is now available for purchase/download at the AES library


I sure hope it's not an engineering report, anchors were used extensively and Bob has his credentials in order.
Loudspeaker manufacturer

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #20
The Stuart AES Convention paper is now available for purchase/download at the AES library


I sure hope it's not an engineering report, anchors were used extensively and Bob has his credentials in order.


It's a convention paper -- so, not even peer reviewed.  (It's also a completely in-house affair -- all three authors work for Meridian). 

Thus, I expect Our Man from  Madrona will reject it forcefully, using at least three if not four different font colors.

 

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #21
Krabapple, you bought the paper? I see your quote in the AVS forum of more than just the abstract, for example.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #22
Did he give an explanation why rectangular dither was used instead of triangular, considering it is know to introduce noise modulation which triangular is immune from?

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #23
Krabapple, you bought the paper? I see your quote in the AVS forum of more than just the abstract, for example.


Yes.  I've bought lots of AES papers over the years.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #24
Did he name the sampling rate convertor model number?  If so, if in its owner's manual it mentions, say: "Be advised the optional use of rectangular dither [RPDF or "Rectangular Probability Density Function,"] instead of TPDF, may cause audible noise modulation", then he's dead meat.

How about absolute SPL used for the tests? Source songs? Source machine? Does he/they mention checking for time misalignment which we now know some SRCs introduce? Level matching after the conversion? Remember the SRC used by AIX for the AVS forum test introduced BOTH level and time alignment problems which I proved is audible.