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"Audiophile" listening event @ Definitive Audio in Seattle, Atkinson to demonstrate "evils of MP3"
Stereoeditor
post Feb 11 2011, 23:23
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QUOTE (spoon @ Feb 11 2011, 17:06) *
Any step of signal processing could introduce the artefacts, such as the resampling.


I felt that resampling the reduced-data-rate files back to 24-bit/88.2kHz would eliminate the DAC and reconstruction filter as confusing variables. There would also then be no visible indication to listeners, such as the DAC sample-rate LED changing state, that the file format had changed. It also allowed me to splice the four examples together so that there was no clue anything had changed other than the possible change in sound quality. The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3. Only after the music had finished playing did I ask them for their reactions and tell them what they had been listening to.

John Atkinson
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Stereoeditor
post Feb 12 2011, 16:25
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QUOTE (mixminus1 @ Feb 11 2011, 16:18) *
John, IIRC you've been doing your recording at 24/88.2 for awhile now, and I know that Stereophile has sold CDs through at least one third-party vendor, Acoustic Sounds. How about making your high-res recordings available through HD Tracks?


I have actually had an agreement with HDTracks agreed in principle for a year, but the legal obstacles on my end have proved more difficult to resolve than i had anticipated.

QUOTE
As an alternative, would you be willing to post <30 sec. FLACs of what you consider to be the most "challenging" or "revealing" passages of the tracks you used? I understand if legal issues prevent you from doing so, but I really would like to be able to try my own ABX of at least some of the material you used, and I suspect others on this forum would, as well.


Unfortunately, when I have allowed others access to some of my master files in the past, some have abused the privilege, so I am wary of doing so again, I am afraid. On the other hand, the example I used in Colorado and Seattle was the chorus "For Unto Us a Boy is Born," from the Dunedin Consort's recording of Handel's Messiah, which is available as a 24-bit/88.2kHz FLAC download from Linn Records for a couple of dollars. It was recommended to me by Linn's engineer Philip Hobbs a a good choice for revealing problems.

John Atkinson
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Stereoeditor
post Feb 12 2011, 16:28
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QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say. (I waited too long to correct the omission.)

John Atkinson
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This post has been edited by Stereoeditor: Feb 12 2011, 17:27
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odyssey
post Feb 12 2011, 16:45
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QUOTE (Stereoeditor @ Feb 12 2011, 16:28) *
QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say.

John Atkinson
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From your choice of encoders/bitrates, I'd guess you already decided for yourself that AAC is superior...

This post has been edited by odyssey: Feb 12 2011, 16:45


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Stereoeditor
post Feb 12 2011, 17:24
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QUOTE (odyssey @ Feb 12 2011, 10:45) *
QUOTE (Stereoeditor @ Feb 12 2011, 16:28) *
QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say.

From your choice of encoders/bitrates, I'd guess you already decided for yourself that AAC is superior...


I chose the bitrates and formats because AAC at 320kbps is the highest bitrate supported by the iTunes/Quicktime engine and MP3 at 128kbps is typical commercial download practice. But presumably it would be a ToS#8 infringement if I were to comment on what I feel the audible differences were.

John Atkinson
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knucklehead
post Feb 12 2011, 17:51
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QUOTE (Stereoeditor @ Feb 12 2011, 08:24) *
But presumably it would be a ToS#8 infringement if I were to comment on what I feel the audible differences were.


Not if you supply ABX results to show why you "feel" that way.
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Notat
post Feb 12 2011, 19:57
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QUOTE (Stereoeditor @ Feb 11 2011, 12:12) *
QUOTE (spoon @ Feb 11 2011, 11:53) *
QUOTE (Stereoeditor @ Feb 11 2011, 13:05) *
QUOTE (Notat @ Feb 10 2011, 11:04) *
I wasn't there either. I would be very interested in seeing Krabapple's questions answered.

Had you been there - had _anyone_ from HA been there - you would have known what happened at my presentation. I am puzzled by the fact that there exists simultaneously much curiosity about my Seattle presentation but not enough curiosity for anyone to attend. The same phenomenon occurred when I gave a similar presentation in Colorado 2 years ago. As I said, the next time I give a presentation like this, I'll give HA plenty of notice in case someone wishes to and is able to attend.

Are there reasons for you not wanting to answer the questions regarding which encoder, bitrate, etc was used to create the mp3 files?

Only that I did answer at length on HA the same questions, including those put to me by"krabapple," when I did the same demonstration in Colorado 2 years ago. See, for example, http://www.hydrogenaudio.org/forums/lofive...p/t71245-0.html . See also http://www.hydrogenaudio.org/forums/index....72446&st=25 .

There a lot of stuff to wade through there so correct me if I pulled out the wrong bit. This post describes a sequence of resolutions from 88.2 kHz/24-bit to 128 kbit MP3. Listeners are apparently asked single-blind and en masse whether quality improves or degrades during playback. It has been previously demonstrated that 128 kbit MP3 is not transparent. This is not a difficult test for most listeners to pass and even if it is for for a particular listener, they have a bunch of other listeners and (since it is single blind) possibly the administer of the test to coach them to the correct answer.
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odyssey
post Feb 12 2011, 20:16
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QUOTE (Stereoeditor @ Feb 12 2011, 17:24) *
QUOTE (odyssey @ Feb 12 2011, 10:45) *
QUOTE (Stereoeditor @ Feb 12 2011, 16:28) *
QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say.

From your choice of encoders/bitrates, I'd guess you already decided for yourself that AAC is superior...


I chose the bitrates and formats because AAC at 320kbps is the highest bitrate supported by the iTunes/Quicktime engine and MP3 at 128kbps is typical commercial download practice. But presumably it would be a ToS#8 infringement if I were to comment on what I feel the audible differences were.

John Atkinson
Editor, Stereophile

The very same could be said for AAC, although iTunes Plus uses 256kbit. Still, I don't really understand what you are trying to prove with these selections. If you want to prove ANYTHING by the choice of codec, for the matter of AAC and MP3, you should definitely provide samples at the same bitrate.

Using your argument also perfectly fits mp3 - I don't know of an "mp3 engine" that is not able to decode 320kbit mp3.


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greynol
post Feb 12 2011, 20:31
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QUOTE (Stereoeditor @ Feb 12 2011, 07:25) *
On the other hand, the example I used in Colorado and Seattle was the chorus "For Unto Us a Boy is Born," from the Dunedin Consort's recording of Handel's Messiah, which is available as a 24-bit/88.2kHz FLAC download from Linn Records for a couple of dollars.

Please provide the time within this specific track (relative to the beginning of the track in mm:ss) where the difference between lossless and lossy is most obvious so that someone can provide a 30 second clip.

This post has been edited by greynol: Feb 12 2011, 20:32


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krabapple
post Feb 12 2011, 21:27
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QUOTE (Stereoeditor @ Feb 12 2011, 10:28) *
QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say. (I waited too long to correct the omission.)

John Atkinson
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But were they apprised in any way, shape or form, e.g., via the title of the presentation, the advertising or promotion for it, or anything said by way of as introduction, that your appearance would be at least partially about the sound of audio formats?

And did you continue to use Audition 1.0's not-at-all-current mp3 codec?

And did you again only solicit and note responses, such as they were, after the final (128 kbps) segment?

And if anyone in the audience said something like , 'wow, I really heard a dropoff in quality', what if any explanation did you offer?

Was the role of expectation bias in audio quality assessment mentioned at all?

This post has been edited by krabapple: Feb 12 2011, 21:29
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krabapple
post Feb 12 2011, 21:35
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QUOTE (Stereoeditor @ Feb 12 2011, 11:24) *
QUOTE (odyssey @ Feb 12 2011, 10:45) *
QUOTE (Stereoeditor @ Feb 12 2011, 16:28) *
QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say.

From your choice of encoders/bitrates, I'd guess you already decided for yourself that AAC is superior...


I chose the bitrates and formats because AAC at 320kbps is the highest bitrate supported by the iTunes/Quicktime engine and MP3 at 128kbps is typical commercial download practice. But presumably it would be a ToS#8 infringement if I were to comment on what I feel the audible differences were.

John Atkinson
Editor, Stereophile



I question whether 128 kbps is still typical for commercial download; certainly iTunes moved on from it as default long ago. Amazon's default is 256 kbps VBR.


And including a difference demo as a form of 'training' is just wrong for all the reasons noted in the Massenburg thread. And under those circumstances failing to explain how psychoacoustics-based lossy encoding works and what it is SUPPOSED to do, would be misleading at the very least and dishonest at worst.

This post has been edited by krabapple: Feb 12 2011, 21:39
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Stereoeditor
post Feb 12 2011, 21:36
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QUOTE (greynol @ Feb 12 2011, 14:31) *
QUOTE (Stereoeditor @ Feb 12 2011, 07:25) *
On the other hand, the example I used in Colorado and Seattle was the chorus "For Unto Us a Boy is Born," from the Dunedin Consort's recording of Handel's Messiah, which is available as a 24-bit/88.2kHz FLAC download from Linn Records for a couple of dollars.

Please provide the time within this specific track (relative to the beginning of the track in mm:ss) where the difference between lossless and lossy is most obvious so that someone can provide a 30 second clip.


This download is unadulterated 24-bit/88.2kHz, of course. Following the instrumental introduction, the refrain repeats 3 times. For the version I used in my demonstration, each time the sopranos or tenors begin the verse "For unto us a boy is born" after the first -- at 1:22, 1:57, 2:38 -- I spliced seamlessly to the next version encoded with a different codec.

I am not sure how I can answer your question without conflicting with ToS#8, as I haven't tested my opinion with ABX. However, for what it's worth, I felt the sections where the choir sing "and the government shall be upon his shoulders" -- starting at 55:00, 1:33, 2:12, 2:53 -- were the most vulnerable.

John Atkinson
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spoon
post Feb 12 2011, 21:40
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For what is it worth 128kbps is no longer the offered download bitrate, a few recent Amazon tracks were Lame -v0 (aroud 256kbps) some of the others tend to use 320kbps CBR, for practically everyone these bitrates are transparent (unless specific problem tracks are used).

The days of having a mp3 player which could only store 2 albums at 128kbps have passed 10 years ago, now iPods can store whole libraries at 320kbps.

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greynol
post Feb 12 2011, 21:44
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QUOTE (Stereoeditor @ Feb 12 2011, 12:36) *
I felt the sections where the choir sing "and the government shall be upon his shoulders" -- starting at 55:00, 1:33, 2:12, 2:53 -- were the most vulnerable.

So a 30 second clip centered at any of these times (assuming you meant 0:55 for the first one) should be acceptable?

Would you be willing to perform an ABX test and present your results as an effort of good faith?

This post has been edited by greynol: Feb 12 2011, 21:45


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mixminus1
post Feb 12 2011, 21:48
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Downloaded and standing by...

Edit: OK, I guess our Saturday morning coffee is kicking in smile.gif - hot topic, indeed!

Here is the link to a 24 second section from 1:21-1:45 (the most I could fit into 8 MB, the upload limit), which encompasses both one of the sections John used in his presentation at Definitive, as well as one of the sections he feels is most revealing:

http://www.hydrogenaudio.org/forums/index....showtopic=86738

This post has been edited by mixminus1: Feb 12 2011, 22:28


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Stereoeditor
post Feb 12 2011, 22:28
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QUOTE (greynol @ Feb 12 2011, 15:44) *
QUOTE (Stereoeditor @ Feb 12 2011, 12:36) *
I felt the sections where the choir sing "and the government shall be upon his shoulders" -- starting at 55:00, 1:33, 2:12, 2:53 -- were the most vulnerable.

So a 30 second clip centered at any of these times (assuming you meant 0:55 for the first one) should be acceptable?


I imagine so. And yes, 0:55. Apologies for the error.

QUOTE
Would you be willing to perform an ABX test and present your results as an effort of good faith?


Why would that be necessary? As I said, the answer to your question implicitly involved a ToS#8 violation. I believe I showed sufficient good faith in offering an answer, in order that others might try this musical passage for themselves.

John Atkinson
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Stereoeditor
post Feb 12 2011, 22:36
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QUOTE (krabapple @ Feb 12 2011, 15:27) *
QUOTE (Stereoeditor @ Feb 12 2011, 10:28) *
QUOTE (Stereoeditor @ Feb 11 2011, 17:23) *
The listeners, BTW, were not told before the music segment started playing that they would be listening to four different formats, 24-bit/88.2kHz, 16-bit/44.1kHz, 44.1kHz AAC at 320kbps, 44.1kHz MP3.


MP3 at 128kbps, I meant to say. (I waited too long to correct the omission.)


But were they apprised in any way, shape or form, e.g., via the title of the presentation, the advertising or promotion for it, or anything said by way of as introduction, that your appearance would be at least partially about the sound of audio formats?


Other than the text included in the title of this thread, no. All the attendees were told was that they were going to be listening to some of my hi-rez recordings.

QUOTE
And did you continue to use Audition 1.0's not-at-all-current mp3 codec?


No.

QUOTE
And did you again only solicit and note responses, such as they were, after the final (128 kbps) segment?


Yes.

QUOTE
And if anyone in the audience said something like , 'wow, I really heard a dropoff in quality', what if any explanation did you offer?


I explained what they had been listening to. After the event, not before.

QUOTE
Was the role of expectation bias in audio quality assessment mentioned at all?


As a general point, how can there be any expectation bias if the listeners are ignorant of what they will be listening to? And in this case, as all that people knew was that would be listening to a 24-bit 88.2kHz audio file, if there were any expectation bias, surely it would be in the opposite direction, ie, it would tend to make them _less_ critical of the lossy codecs?

John Atkinson
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greynol
post Feb 12 2011, 22:43
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The good faith would be in your finally taking part in what is an acceptable method of testing lossy audio codecs as deemed by those who actually develop them.


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Arnold B. Kruege...
post Feb 12 2011, 23:16
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QUOTE (Stereoeditor @ Feb 9 2011, 17:24) *
QUOTE (Arnold B. Krueger @ Feb 9 2011, 17:11) *
QUOTE (Stereoeditor @ Feb 9 2011, 15:17) *

And who could object to an event that promotes the idea of listening to recordings with as high a quality as possible?


Does one have to leave the comfort of one's own home to listen to such a thing?


They do if they wish to hear the hi-rez master files of my own commercial recordings...


So then it is your assertion that all other forms of those files sound degraded, or at least different?

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Arnold B. Kruege...
post Feb 13 2011, 00:10
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QUOTE (greynol @ Feb 12 2011, 16:43) *
The good faith would be in your finally taking part in what is an acceptable method of testing lossy audio codecs as deemed by those who actually develop them.


I think we should be a little more broad-minded than that. It is possible that the developers of lossy codecs have overlooked some signficiant new technology for doing sound quality evaluations. Thing is, any such technology would have to be significantly different from the methodologies that we already know, and some of us know very well.

Seeing no such thing... ;-)
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greynol
post Feb 13 2011, 00:32
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I will happy await comments from members such as robert, Gabriel, menno, muaddib, Monty, r2d, Seed, C.R.Helmrich and Nick.C about the methods they use. One should not underestimate the impact HA has had on the development of lossy codecs.

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mixminus1
post Feb 13 2011, 03:08
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Well, I just did some back-n-forth listening tests in foobar2000 between the 24 sec. FLAC sample and two 44.1 kHz LAME V2 (VBR @ ~190 kb/s) MP3s, one from a 24-bit WAV, one from a 16-bit WAV...didn't get to ABX-ing because I couldn't hear anything to ABX. I used my Sony MDR-V6 headphones being driven by the onboard RealTek HD audio of my PC (using udial and loop-back recording, I determined that setting fb2k's resampler to 88.2 kHz and its bit depth to 24 bits gave the most accurate output, and the noise floor of the headphone out is inaudible).

I downconverted to 24/44.1 and 16/44.1 WAVs using fb2k's resampler in "ultra" mode (and added dither for the 16-bit version) and then encoded those to VBR V2 MP3s using LAME (yes, I could've done that in one step but I wanted to have the WAVs in case I heard something suspect in the MP3s).

FWIW, the overall bitrate of the MP3 from the 24-bit WAV was 193 kb/s, and from the dithered 16-bit WAV it was 190 kb/s.


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Stereoeditor
post Feb 13 2011, 15:11
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QUOTE (Arnold B. Krueger @ Feb 12 2011, 17:16) *
QUOTE (Stereoeditor @ Feb 9 2011, 17:24) *
QUOTE (Arnold B. Krueger @ Feb 9 2011, 17:11) *
QUOTE (Stereoeditor @ Feb 9 2011, 15:17) *

And who could object to an event that promotes the idea of listening to recordings with as high a quality as possible?


Does one have to leave the comfort of one's own home to listen to such a thing?


They do if they wish to hear the hi-rez master files of my own commercial recordings...


So then it is your assertion that all other forms of those files sound degraded, or at least different?


With respect, Mr. Krueger, any answer to your question would necessarily involve a ToS#8 violation. All I can do is refer you to my writings in Stereophile on this subject.

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googlebot
post Feb 13 2011, 16:08
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QUOTE (Stereoeditor @ Feb 13 2011, 15:11) *
With respect, Mr. Krueger, any answer to your question would necessarily involve a ToS#8 violation.


By simple inference from this sentence: John Atkinson admits that anything he can claim in favor of hi-rez audio is necessarily impossible to backup by objective evidence or scientifically established practice to exclude placebo side-effects.

I can live with that and he can continue to sell his magazines (and advertising space).
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PaJaRo
post Feb 13 2011, 16:16
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QUOTE (googlebot @ Feb 13 2011, 16:08) *
QUOTE (Stereoeditor @ Feb 13 2011, 15:11) *
With respect, Mr. Krueger, any answer to your question would necessarily involve a ToS#8 violation.


By simple inference from this sentence: John Atkinson admits that anything he can claim in favor of hi-rez audio is necessarily impossible to backup by objective evidence or scientifically established practice to exclude placebo side-effects.

Not exactly, that only means he can't ABX the differences.
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