Thus spake Jim Lesurf:
snipped
If subjects can't hear fairly large differences in a calibration
cycle, I can envisage 2 explanations. Firstly, some/many/most
subjects are fairly insensitive to variations & by definition, would
be wasting money by buying expensive audio equipment for sonic
reasons alone.

That may be so. However, if so, we would then have to be cautious
about trying to draw specific/individual conclusions from the above
as it is a generalisation. So some people *might* be able to hear
*some* differences when others cannot.

A maddeningly large sample may be needed.

But to see if this is the case, we would first need some test
subjects to demonstrate in a suitable test that *they* *can* hear a
given 'difference' even if (many) others cannot. Otherwise the
simplest hypothesis consistent with results may be that - despite
claims to the contrary - *no one* can hear a given 'difference'.

Indeed. There may well be a large variation in subject's auditory
sensitivity according to age, how critical their listening had been etc. I
would still be very suspicious *if* subjects can't hear large introduced
differences. If a number of subjects *can* hear calibrated differences but
can't hear any during the real part of the test, that would certainly point
towards the effectiveness of DB testing & would by definition, render my
worries regarding memory effects as being irrelevant. *Testing the test by
using a cal cycle is crucial to my mind.*

The second, is that because the way the mind works, comparing
sequences such as replaying the same piece of music is going to
confuse the subjects & muddy the results. I can imagine this
explanation being very inconvenient to many because it throws in
hidden variables such as how reliable human memory is & its effects
on the outcome. I only entertain this possibility because my own
experience suggests measuring qualitative stuff can be damned
difficult. A lot of people also state they can hear differences
beyond measurability.

The problem with the above is as follows:

IIUC there is good evidence to the effect that our memory and state
of mind affect what we notice, or how we perceive or judge what we
experience.

Agreed. Some people even concoct whole events such as alien abduction,
invent the concept ritual child abuse, implant false memories etc.
Attributing differences in audio equipment would be picnic in the park -
hence the need for some kind of testing.

This may be a reason for saying that 'time serial' comparison tests
are affected by this, so tending to reduce the noticibility of real
differences.

Yup. I've repeated a section of music & concluded that I couldn't tell that
both plays sounded the same or not!

However this may also mean that people hear 'differences' which are
due simply to their change in mental (or physiological) state, etc.
Thus they may be saying that one item sounds different to another
when the actual sounds produced are unchanged.

Again yes. Some form of testing would be needed to average out the noise.

Thus the same 'mechanism' produced to 'explain' why such tests tend
to show people unable to hear a difference also 'explains' why they
may think they hear differences in situations where none really
exists.

The upshot being that we then have no reliable evidence that any such
differences exist. But plus having a reason for saying that what
people claim may be based on an error.

This would also give us grounds to say, "since the perceptions are
variable, there is no real point in worrying about differences so
slight at to fall within these variations".

Thus we end up with "a differences which makes no difference *is* no
difference". (Spok's Rule.) :-)

Very much a possibility that occurred to me last night! The memory effect
biting back by masking - even if it could be proved that some differences
not shown in BT tests but in some other one did exist they may well be
fairly pointless in that they simply get drowned within the noise of
perception. I didn't want to throw in too many of my own objections,
otherwise I'll be accused of sock puppetry within the same message!

The advantage of some of the ABX forms of test is that the
comparisons can be done on all sorts of time scales - under the
control of the test subject. So they can switch quickly if worried
about 'memory' or drifts in their physiology, etc. For some kinds of
difference this seems IIRC to produce enhanced sensitivity. But for
others it shows no sign of the subjects being able to hear any
difference, on any timescales people have employed.

Months? I ask because I've either replaced or upgraded equipment, listened &
made a mental note that I could hear no differences then forgotten about it.
Months later, I've played a particular piece of music to be struck by how
different it sounds.

I heartily wish I could suggest alternatives but I can't.

Well, from the POV of the scientific method a hypothesis has to be
testable to have any validity/meaning. So if you/someone can't
propose and carry out an appropriate alternative we have to stick
with hypotheses we *can* test. This is to avoid people simply
believing whatever they choose, regardless of the reality.

But only if the tests are valid & don't end up perpetuating a
fallacy. If it meant going back to the drawing board, so be it.

The problem with *if* here is that it is a speculation. That has no
real use in the scientific method *unless* you can then propose a
test which would distinguish you hypothesis from the competing ones...

Thus a given test *might* not be 'valid'. But to decide this would
require a suitable test, ideally also a proposed 'mechanism' for the
cause of the lack of 'validity' which the new test would probe.

You make it seem that I advocate rolling dice Yes, of course it's more
satisfactory to forward a displacing theory rather than merely suggesting
the existing one is flawed but where would we be if someone was to suggest
that lead in cosmetics was dangerous & others said that they would continue
using it until the doubter came up with a substitute. As for speculation
Jim, much good science has come from it.

Without that, we have to work on the basis of using the hypotheses
that are consistent with the evidence we have, and trying to avoid
adding mechanisms which the evidence does not require, or ideas we
cannot test.

Many things *might* be the case. But that does not tell us they *are*
the case. For that we require relevant evidence. Alas, "the evidence
does not agree with my beliefs" is not actually evidence... :-)

Until someone comes up with a watertight explanation why DB is infallible or
near as dammit so, I'll reserve the right to be sceptical in the same manner
that I've been sceptical of my own hearing. To sum up, I'm not suggesting
that DB testing is completely pointless but IMO, can't be relied upon as the
sole means of testing, especially when some use it as a club to bash people
with the idea that most equipment sounds essentially identical. I feel more
comfortable with folks being cloth-eared than folks having so-called golden
ears!

--
Basically, I hate people who preface most sentences with "Basically...