In article ,
ScottW wrote:
On Thursday, September 26, 2013 4:48:40 PM UTC-7, Audio_Empire wrote:
In article ,
ScottW wrote:
I never understood this point. If one doesn't think they hear a
difference...what is point of proving that they do?
For the individual, there would be no such point, but the purpose of a
bias controlled test is to obtain a statistically significant result as to
whether there actually exists audible differences or not. Humans are very
subjective creatures. We can talk ourselves (either consciously, or
subconsciously) into hearing - or not hearing - a myriad of things just
because we WANT to hear or not hear them.
Exactly. So how do you expect to get a rational response from a person who
hears no difference in identifying one (same to him/her) sound from another?
It's not a reasonable request.
Well, theoretically, if the listener does not know what he is listening to, then
he leaves his expectational biases at the door. For instance, if he knows that
one cable he is auditioning costs thousands of dollars and the other costs $5,
then he is going to hear that the expensive one sounds better - every time.
But when he doesn't know what he's listening to, and just knows that he is
comparing two cables, then it comes down to whether or not he can detect when
the two samples are switched in and out of the test system. If he can't over a large
number of tries, then it is assumed that no difference between the two sample
exists, and if he can tell the difference over a statistically high number of tries,
then it is assumed that some difference does exist.
But all of this depends so much on how the tests are set-up and run, and the
environment in which they are held, and who is participating (what are the p
articipant's personal agendas, if any? There are people who post here who I wouldn't
let participate in a DBT, because their personal agenda is to find NO difference
between any two of anything). All of this makes DBTs of audio gear somewhat
suspect in my mind.
For instance, if a guy spends
$4K on a pair of interconnects to go between his preamp and his amp,
believe
me, they ARE going to be the biggest improvement he ever experienced with
his system. Even if in a subsequent DBT he can't tell the difference
between
his new $4K babies and a set of Radio-Shack $5 specials, he will swear that
the high-priced cables improved his system's sound. There are people
who post here regularly who have convinced themselves that everything
pretty much sounds the same - even when a DBT shows otherwise. But they
have painted themselves so deeply into that corner, that they REFUSE to
hear
differences even when those differences are very easy for anyone to hear
because they are so gross (like with speakers).
And how does a test overcome such a refusal? You can't make a dishonest
subject honest when all they need do is fabricate random responses.
Yes that's true. As far as I'm concerned, it makes DBTs for audio somewhat
suspect as we're not dealing with concrete results. In medicine, DBTs are used
routinely to test new drugs. There are usually two groups, one of which gets
the real drug, and the other (called the control group) gets a placebo. The people
taking part in the test don't know which group they are in and the people
dispensing the drugs don't know which participants are getting the placebo and
which are getting the real drug. Someone, way up the line knows which is which,
but even they just know the participants by number - not by name. The results of
these tests compare results with the control group to see if the new drug is statistically
effective. IOW, either the drug taking group has a change in symptoms compared
with the control group, or they don't. The results are pretty unambiguous as there
is simply no way to fake a result. Audio relies on people's impressions and there
is no way to really weed out those people who have an agenda or who are basically
dishonest in their approach to hearing audio components.
Plus...when they produce a null and you produce a positive...you get to
claim the golden ear with test results to prove it 
.
Oh yeah, and it's done all the time, I'm sure of it. Those who believe firmly in
the Julian Hirsch philosophy that everything sounds the same seem to put more
stock in DBTs than do those who believe that all audio equipment sounds different.
This dichotomy is further confused by the fact, that in some cases, the DBT results
and physics agree - like with cables and interconnects. All DBTs with which I'm
familiar, always return a null result. Physics says that a wire is a conductor and in
lengths used in domestic audio situations can have NO effect on the signal passing
through that conductor. Measurements confirm this. But that doesn't mean that
because DBTs accurately show that cable "sound" is bogus, that they are equally
accurate when they give a null result with more complex systems.
I would suggest that a person who doesn't think they can hear a
difference is
simply not a good subject for such a test.
Yes. That is true, but still, that's something that is hard to determine
beforehand.
It's hard to ask a person...do you think you hear a difference sighted?
Exactly.
Even if you don't believe that they can't hear a difference, what is the
point in trying to prove they do? All you could prove with great effort
is
they're being deceptive which would only disqualify them from the
test....something you should have concluded when they said they can't
hear a
difference.
Yes, but if I understand your question correctly, the way that properly
executed DBTs are designed (or at least the way I understand it), one
or two tin-eared listeners out of many and over many tries, won't,
appreciably,
alter the results. Also, most people who take part in these tests probably
don't know beforehand whether or not that can hear a difference. Some, of
course, will go into such a test determined to NOT hear a difference even
when one exists. Statistically, their results won't make any difference to
the
outcome either. The general wisdom with DBTs seems to be that one either
hears a difference between the devices under test or one doesn't. I'm
convinced that in most cases, a statistically positive result can probably
be very accurate, I'm less sure about a statistically negative result.
I think you're mixing apples and oranges in tests.
I'm thinking of the question, can one individual provide reasonable
statistical evidence they can hear a difference? A person who doesn't
believe they can sighted is not a candidate for such a test.
Large numbers of trials with one subject produces only a result relevant to
that subject which is still interesting to me. I'm actually less interested
in general population results which makes the challenge much less daunting.
Large numbers of trials with many subjects (which, IMO, need to be conducted
one subject at a time if only to control for listening position...mass
subject trials are for show) are pretty rare and are for extrapolating
results to the general population. Given the lack of general interest in
high end audio...who really cares what the general population thinks?
It's a significantly different question and one far more difficult to answer
so I ask...why bother?
Well, there is that....
ScottW