LISTSERV mailing list manager LISTSERV 16.0

Help for ARSCLIST Archives


ARSCLIST Archives

ARSCLIST Archives


ARSCLIST@LISTSERV.LOC.GOV


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

ARSCLIST Home

ARSCLIST Home

ARSCLIST  January 2008

ARSCLIST January 2008

Subject:

Re: A/B testing: another approach

From:

Marcos Sueiro Bal <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Mon, 28 Jan 2008 13:56:28 -0500

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (230 lines)

It seems we are re-creating (albeit in a more civilised manner) the 
Great Debate in audio between Objectivists and Subjectivists.

http://www.stereophile.com/news/050905debate/

I believe tests have been performed where users are allowed to take the 
ABX box to their home system and switch as often or as little as they 
want, and take as long or as short as they want (weeks, for example). 
The results were actually less accurate than in standard "short" ABX 
tests (perhaps because of the well-documented effect of one getting 
"used" to the sound of certain equipment).

I believe my Marantz sounds better than my Yamaha amplifier, but lately 
I have begun to suspect that the way the Marantz looks and feels, as 
well as my own believes, etc etc affect my perception. The act of 
listening is a combination of the ear and the brain, but the auditory 
part of the brain is not isolated from other stimuli, so it seems 
logical to think that they may affect how I hear. So in a way, it does 
sound different --in a very real way. But take away the visual stimulus, 
and it ceases to sound different.

As professionals, however, we have to be concerned with subjectivity and 
accurate transfers. So my own ideal strategy when choosing a piece of 
equipment would be:

1 - If there are metric differences (e.g. lower measured harmonic 
distortion), then I will use the equipment with "best specs" I can 
afford, even if I cannot tell the difference; else,

2 - If there are peer-reviewed, well-designed scientific studies (of any 
sort, not just ABX) that show preferences (or differences) perceived 
among a large or important enough group, I will use the perceived 
"better" piece; else,

3 - I will try to determine any perceived differences in my own setup 
via blind testing.

This is my ideal algorithm, but of course the three steps all affect 
each other (e.g. Am I willing to spend $3000 extra on an amplifier that 
shows a minimally better THD number, even if I know no one can ever 
consistently tell the difference?). It seems pretty rational.

This has been an interesting discussion. Thank you.

Marcos

Malcolm Davidson wrote:
> For many people the brain's ability to perceive subtle difference is
> severely limited when the samples are played sequentialy.  It's difficult to
> remember the "reference" track and the one being listened to in the moment.
> For large difference it is much easier so that a sequential test does have
> some validity comparing say 96 KHz 24 bit, CD and MP3.
>
> When we did all the SDMI (Secure Digital Music Initiative)  watermark
> evaluations, not only were we evaluating the watermarking technologies, but
> we were also (unintenionally) evaluating the abilities of the participants.
> This varied widely amongst all the so called experts.  With a certain amount
> of training people can improve their listening skills.  We observed
> individuals who were perceived as "golden ears" who could not pick out a
> watermark, whereas there were some participants who could pick out certain
> watermarks with ease, yet did not have a reputation as an expert listener.
>
> Any type of comparative listening test is highly subjective for the brain
> can pick out subtelties that we are not skilled at measuring. For example
> bit for bit identical streams have been consistantly thought of as different
> by expert listeners,  (separate files on a hard disk)   due in part to the
> buffering and speed matching of the data as it is read off the disk.  It
> changes the small amount of jitter of the digital stream which subsequently
> alters the noise floor of the D/A.  This has influences the spacial imaging
> slightly of stereo.  However many people might describe it differently and
> it might not necessariy be a bad thing.  With the complexity of the "supply
> chain", to the end user,  how close does the final product replicate the
> actual recording experience and do people care and are they willing to pay
> for it?
>
> Malcolm Davidson
>
> ----- Original Message ----- 
> From: "Matthew Barton" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, January 28, 2008 11:30 AM
> Subject: Re: [ARSCLIST] A/B testing: another approach
>
>
>   
>> It wasn't a scientific experiment--just an engineer having a bit of
>> fun--though he seems to have had a point to make, if not a detailedl
>> hypothesis to test. I just thought the structure was interesting, and
>> worth considering if our goal is to develop a listening test or tests.
>> Perhaps the thing that I find most interesting here is that it involved
>> a real-time, uninterrupted  listening experience of A, B, C, and D.
>> Perhaps the brain does respond differently to such a listening
>> experience.
>>
>> Matthew Barton
>> MBRS
>> The Library of Congress
>> 101 Independence Ave., SE
>> Washington, DC 20540-4696
>> 202-707-5508
>> email: [log in to unmask]
>>
>>     
>>>>> Marcos Sueiro Bal <[log in to unmask]> 1/28/2008 10:40:58 AM >>>
>>>>>           
>> Matt,
>>
>> This is an interesting link, but as a scientific experiment it does not
>>
>> seem very useful: What is the hypothesis? How are we quantifying it? A
>>
>> statement such as "my fellow listeners appeared to be equally
>> uncomfortable" does not seem conducive to analysis.
>>
>> If the highs were perceived not to be "as silky smooth" --in other
>> words, if the differentiating factor has been identified after just one
>>
>> listen of a short passage--, should not the same listener be able to
>> correctly identify such a difference in a blind test? Logic seems to
>> indicate that he should, but perhaps the brain works in mysterious
>> ways.
>>
>> Incidentally, it seems that not all ABX tests have concluded that
>> listeners are less sensitive than we thought. I was told in school that
>>
>> most average Joes can hear at most a difference of 1 dB, but a group of
>>
>> 5 listeners in an ABX test perceived differences of 0.4 dB 93% of the
>> time (note: this is not a peer-reviewed paper, and this is from the ABX
>>
>> web page, so it is not conclusive evidence).
>>
>> http://www.provide.net/~djcarlst/abx_lvl.htm
>>
>> Cheers,
>>
>> marcos
>>
>> Matthew Barton wrote:
>>     
>>> Here's a link to an article from the October issue of Stereophile,
>>>       
>> in
>>     
>>> which an interesting approach to blindfold testing is described:
>>>
>>> http://www.stereophile.com/asweseeit/1007awsi/index.html
>>>
>>> This is not an analog vs. digital article, and I'm not endorsing the
>>> test or or its results, or any conclusions in the article, but I
>>>       
>> think
>>     
>>> the approach is interesting. Instead of an A:B comparision, in which
>>> listeners first heard A, and then B, and were asked for opinions,
>>>       
>> this
>>     
>>> engineer created a composite patchwork of different formats using a
>>> repetitive passage from a recent recording of Handel's Messiah. He
>>> didn't tell his audience that this is what they would be hearing:
>>>
>>> "It turned out that we'd been unwittingly involved in a blind
>>>       
>> listening
>>     
>>> test. The DVD-A was a ringer. Philip had chosen a Handel chorus in
>>>       
>> which
>>     
>>> the same music is heard four times. He had prepared four versions of
>>>       
>> the
>>     
>>> chorus—the original 24-bit/88.2kHz data transcoded straight from
>>>       
>> the
>>     
>>> DSD master; a version sample-rate–converted and decimated to
>>>       
>> 16/44.1
>>     
>>> CD data; an MP3 version at 320kbps; and, finally, an MP3 version at
>>> 192kbps—and spliced them together in that order. The last three
>>> versions had been subsequently upsampled back to 24/88.2 so that the
>>> DAC's performance would not be a variable. The peak and average
>>>       
>> levels
>>     
>>> were the same for all four versions; the only difference we would
>>>       
>> hear
>>     
>>> would be the reductions in bandwidth and resolution. "-- from
>>>       
>> "Watching
>>     
>>> the Detectives," by John Atkinson, Stereophile, October, 2007.
>>>
>>> We can all argue about the specs here, but the most interesting
>>>       
>> thing
>>     
>>> to me is that the changes in the audio unfolded over four iterations
>>>       
>> of
>>     
>>> the same passage of music in the same recording. Listeners were not
>>> asked to use their memory of recording A to appraise recording B,or
>>>       
>> vice
>>     
>>> versa. They heard (or did not hear) the changes as part of
>>>       
>> continuous
>>     
>>> listening experience.
>>>
>>>
>>> Matthew Barton
>>> MBRS
>>> The Library of Congress
>>> 101 Independence Ave., SE
>>> Washington, DC 20540-4696
>>> 202-707-5508
>>> email: [log in to unmask]
>>>
>>>       
>>     

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

February 2020
January 2020
December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
October 2005
September 2005
August 2005
July 2005
June 2005
May 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004
July 2004
June 2004
May 2004
April 2004
March 2004
February 2004
January 2004
December 2003
November 2003
October 2003
September 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003

ATOM RSS1 RSS2



LISTSERV.LOC.GOV

CataList Email List Search Powered by the LISTSERV Email List Manager