Mark DeBellis wrote:
A couple of further ideas to toss out, from an onlooker's perspective
of course.

Quick-switch tests are said to be the most sensitive, therefore best,
yes? Because they permit finer discriminations. An observation: the
ultimate purpose of an audio test is not discrimination per se.

No, but if you can't discriminate between two things, then the
differences between them are irrelevant.

That
is, it's not as if the job that has to be performed here is to
discriminate two sources if they can be, to do the best job of
discrimination we can, as if that were the real goal. The real purpose
of the test is rather to find out what information is available to the
listener in the context of use, or perhaps to estimate an upper bound
on that information.

Well, we know that. That's what the science of psychoacoustics is all
about. Check it out sometime.

It is possible that two sources in the ordinary context of use do not
present different information to the listener, even if there are ways
to set up testing situations (e.g., at higher volume) where a person
could discriminate the sources. All well and good if we do, but it's
not like having a test that permits such discrimination is a valuable
achievement in itself; what we are basically interested in is making
sure that if there are differences of information presented in the
ordinary context of use, then they will show up and get discriminated
in the test.

Question: for all the resolving power quick-switch tests have, for all
the power they have to put the stimulus under a microscope and discern
small differences of detail, are there certain sorts of properties they
are *not* so good at picking up? Is there perhaps a forest-for-trees
phenomenon lurking somewhere out there?

No there is not, according to all experts in the field. Or do you think
you know more than the experts?

Here's an off the cuff example. Suppose I have two digital photographs
that are identical except that one is 1.01 the size of the other.
First I compare them (this is the analogue of the quick-switch test) by
comparing small portions of one with the other. The comparison is set
up in such a way that when I compare a square portion of one with a
square portion of the other, one of them is 1.01 as large as the other.
However, I cannot see the difference because these are small areas and
the difference in size is below my threshold of discrimination.

However, when I compare the wholes I can see the difference in size,
because the difference is now greater than the threshold, since the
whole is much larger than any of those parts.

Irrelevant and off-point visual analogy. Visual analogies don't work.
Ever.

An auditory example would be tempo. Suppose I am listening to two
sources, where the only difference is that one of them has a speed of
1.01 times the other. If I listen to short excerpts any difference is
below the just-noticeable-difference, but if the whole example is the
Ring cycle, I will notice that one finishes before dark and the other
doesn't, I get hungry during one but not the other, etc.

But you're not discriminating between the two by listening to them.
You're discriminating between them by looking at the clock. (And I
don't know what the threshold is for speed variation, but at some point
you really would be able to distinguish between them in a standard
DBT.)

So even if quick-switch tests, on balance, are the most sensitive, that
doesn't mean there can't be things out there that don't get caught in
their net (though they may be detectable in other ways).

So far you haven't come up with a single one. That's because there
aren't any.

To come back to the SACD/CD example, my concern is whether, even if the
quick-switch test were a "null," there could be differences that the
test does not do a good job of proving the existence of. Rather than
feel assured that science tells us there could not be such differences,
it seems to me pretty apparent that every test has its limitations.

Sound plausible?

No. It sounds like you're grasping at straws because you don't like
what the science is telling you. If you live in Kansas, I suggest you
run for the state board of ed.

bob