Harry Lavo wrote:
wrote in message

What you're suggesting here is to connect some component whose identity is
unknown to you and then rate the sound you hear. You describe it as
carefully as you can using the english language. You then have someone
else
connect a competing component, and you once again describe the sound you
hear. You repeat this process for each different component that you have
available. Do I understand correctly?

If so, the test will only be meaningful if you can draw some conclusion
from
the descriptions, and that of course means comparison. There has to be
enough info to decide which component sounds the best, the worst and so
on.
IOW the descriptions have to be useful enough to allow you to rank order
your preference on their basis. Frankly, I don't think you can do this.

It would be even tougher--and probably more embarrassing--if there was the
possibility of repetition, if the units under test were chosen completely
at
random.


Norman, this is done all the time.

Not really. It's done in your field (product testing), but only in
cases where you already have strong reason to believe that perceptions
will at least be *different*, and you want to know in what ways they
are different. No one in his right mind would go to the expense of such
a test unless he were damn sure the things he was comparing at least
tasted different.

This sort of test has never been used, to my knowledge, to do threshold
tests of perception (with the obvious, and hence very dubious,
exception of your Japanese hero).

It simply means devising a series of
meaningful rating scales (usually 1 to 5, low to high) for attributes you
consider important, or adapt the ones developed by others if they seem
satisfactory. Then after each listening session, you rate your impressions
of what you just heard. After a few such sessions with each competing
component in the system and all else held constant, you can begin to get a
feel for differences, if any.

An interesting choice of words: "begin to get a feel for difference."
The statistics of demonstrating a significant difference in threshold
perception using such a test would be mind-numbing, if they were
possible at all. For one thing, you'd need to be able to tell whether
the various factors you are testing for are indeed independent. The
statistics start to grow meaningless very fast if the supposedly
independent variables are not independent of each other.

On the other hand, this is a perfectly logical approach when you know
two things taste different, and you want to know whether your future
customers will find one sweeter than the other, or smoother than the
other, etc.

Of course this is best done blind, but even
sighted it can help quantify perceived differences that are arrived at
monadically and wholly subjectively, with no forced comparison.

If it's not done blind, it can tell you absolutely nothing about the
*sound* of the equipment, because it would fail to exclude some very
obvious and powerful non-sonic influences on those perceptions.

bob