On Fri, 15 Feb 2008 15:43:08 -0800, bear wrote
(in article <fp582c01a2c@[EMAIL PROTECTED]
>):
> Sonnova wrote:
>> On Mon, 11 Feb 2008 16:17:08 -0800, bear wrote
>> (in article <foqoi402tkd@[EMAIL PROTECTED]
>):
>>
>>> Arny Krueger wrote:
>>>> "Greg Wormald" <greg.wormald@[EMAIL PROTECTED]
> wrote in message
>>>> news:folrst02p34@[EMAIL PROTECTED]
>>>>
>>>>> The very set-up of much ABX testing (which is most often
>>>>> short segments of music quickly switched), cannot test
>>>>> for what most music lovers are seeking--long term
>>>>> enjoyment of music listening.
>>>> This is a false claim that I've heard on and off for about 30 years,
now.
>>> Well Arny, where is the correlation between ABX tests and subjective
>>>
>
> <snip>
>
>> onnects are so bad that they cause non-trivial frequency response
>>>> variations, they are by definition, defective.
>>> This would appear to be a true statement.
>>> But it is not.
>>> The reason that it is not true is that the "ABX" tests that have been
>>> touted
>>> as
>>> providing this information are fraught with unknown variables.
>>> Let me list a few for the readers:
>>> - frequency response of the speakers
>>
>> if you are using the SAME speakers for each component under test, the
>> frequency response of the speakers is a constant, NOT a variable and
>> therefore is irrelevant. If you are using different speakers for the
ABX
>> test, then you're doing it wrong by introducing more than one variable
into
>> the test.
>
> You are simply not comprehending the significance of masking due to
> distortion(s) nor the effect of cascaded distortions.
>
> Put it another way, IF the distortions present are of a particular type
or
> class
> then you can put anything you like into the signal chain of lower or nil
> distortion and most likely not be able to identify any change. Since you
have
> no
> way to determine the significance or type/class of distortions in your
> system,
> you don't know anything about the results of an ABX test other than the
> results
> being SPECIFIC to the test you performed.
>
>>
>>> - distortion vs. power vs. frequency for the speakers
>>
>> See above.
>>
>>> - polar response of the speakers vs. frequency
>>
>> Again irrelevant because the cables/interconnects are feeding the same
set
>> of
>> speakers.
>>
>>> - reverberation time vs. frequency of the room
>>
>> Same room for both components under test, the room becomes irrelevant.
>
> That is simply wrong and incorrect IF you wish to generalize the results
> beyond
> the specific test.
>
> Let's do a simple mental excercise on this, ok?
> Put the speakers into a relatively small room made of ceramic tile, do
the
> test
> there. Are those results meaningful? Yes? No?
>
> I assume the answer will be *no*.
> The point is that the room does matter - the question is to WHAT DEGREE.
It
> is
> not irrelevant it is a non-zero factor. If it is not controlled and
known,
> then
> it is a variable whose effect is UNKNOWN. Therefore the validity of the
tests
> is
> compromised and can be called into question.
>
> Obviously, let's not push the thing into absurdity - at some point
things can
> not be known - but the present crop of ABX tests that I know of don't
take
> into
> account relatively simple, basic things that CAN be known.
>
>>
>>> etc. etc. etc....
>>>
>>> EVEN WITH this information, I have yet to read a published ABX test
that
>>> would
>>> permit someone to precisely duplicate the test. Not enough information
is
>>> provided.
>>
>> Not needed. All you need is a system and a way to switch between two
>> different components carrying the same signal at matched levels. This
can
>> be
>> done by a ABX switch box or a third party who either switches or not on
>> command from the listener(s).
>
> If you wish to make this assertion, so be it.
> It is not valid science, nor does it yield particularly useful results
except
> by
> serendipitous result.
>
>>> Show me *one* that has the requisite information and controls.
>>
>> It's really very simple. after matching levels and using the same
source
>> material, merely switch between the two units under test and determine
if
>> you
>> can hear a difference. Listen as long as you like to either or both
>> contenders and decide whether or not you can tell ANY difference
between
>> them. It's that simple.
>
> NOT that simple. Sorry. Wrong.
> For all the reasons stated.
> That test is ONLY valid in the system under test. Period.
>
>>> Dr. Earl Geddes' research - and he is a hardcore
>>> academician/scientist/researcher - has shown that absolute values of
>>> distortion do not translate at all to audibility of distortion.
>>
>> But that's a different discussion and has nothing whatsoever to do with
>> blind
>> or ABX testing.
>
> WRONG. It has *everything* to do with ABX and *all other listening
tests*.
> Read it yourself.
> Re****t back.
> No reason to be ignorant of this new research!!
>
>>
>>> So, the sum total of all this is that ABX is a tool that may or may
not
>>> yield
>>
>>> information that is useful. Period.
>>
>> Well, ABX/Blind testing can really only tell two things: Is there a
>> difference in the sound between two components (or interconnects or
speaker
>> cables)? And if there are differences, what are they? It cannot tell
which
>> is better (assuming that there are differences) as that is a totally
>> subjective call.
>
> That is not being discussed.
>
>>
>> Where this type of testing REALLY falls down is where the differences
are
>> subtle (which they often are) and the listener doesn't have the trained
>> listening a***en to pick-up on those differences. Since there is no way
to
>> eliminate or even pre-screen for this particular variable, the results
are
>> often going to show that there is no difference, when in reality, the
>> listener(s) just missed them or really cannot hear them. The results
never
>> work the other way where the unsophisticated listener reliably and
>> statistically hears differences that aren't there. I'm sure that you
can
>> see
>> why that's so.
>
> Unfortunately, that is NOT what research has shown at all.
>
> You keep insisting on "differences that are not there."
> That is an assertion that may or may not correlate with tests that may
or may
> not be effective at testing what they pur****t to be testing!!
>
> What you want to say is that *you believe* that the majority of
differences
> re****ted by non-ABX test listeners are not real differences. That is
your
> belief, which you are entitled to. There are no tests that adequately
sup****t
> such a point of view. Again, I urge you to actually read at least the
> abstract
> of Dr. Geddes work to understand WHY I keep saying this sort of thing!!
:_)
>
> _-_-bear
I realize that this is usenet and people write stream of consciousness and
for brevity, and often people don't get the points across that they are
trying to convey due to poor wording, omitting certain facts by accident
or,
occasionally out of purposeful obfuscation. Here, to paraphrase an old
Amos
'n Andy radio routine "either I'm not hearing what you are saying, or you
aren't saying what I'm hearing." either way we don't seem to be
communicating. In any substitution test, you are listening for the
differences between two different components of the same type, whether
that
be two preamps, two power amps. two speaker systems or two interconnects.
If
the listeners cannot detect any difference between the sound of the two
units
under test in a statistically meaningful manner after X number of tries,
then
there are NO differences. The rest of the system OTHER than the units
under
test, MUST be identical for both units. You can change out only one
variable
at a time. If the rest of the ancillary equipment is the same for both,
then
any differences perceived must be differences between the two components
in
question, because they are the only two variables. All else being the
same,
these red herrings (if I understand what you are saying correctly) about
room
acoustics, speaker distortion, etc. are irrelevant because (unless you the
speakers are the devices under test) they are the SAME for both test
samples.
If I switch between two preamps, for instance, and hear a difference, then
it
is clearly the preamps which are different, because nothing else has
changed
between the listening of one preamp or the other and the preamp cannot
change
the characteristics of either the room or the speakers.
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