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Why DBTs in audio do not deliver
"Harry Lavo" wrote;
"Audio Guy" wrote in message
...some snips.....
OK, I guess I'll have to explain something I thought was implicit in
this discussion, that the discussion at hand is about audio
reproduction devices, and also add that Elmir, for one, feels that
that music reproduction is the only important factor in the
discussion. But I agree totally with you, music per se has no
relevance to the discussion of the audible differences in audio
amplifiers, only sound.
Wait a minute, wait a minute. Only sound? There is no music until the
brain has processed the sound and interpreted it as music. And that is the
primary reason music reproduction is not simply electrical and physical
engineering. Their is no way to measure *music*. Ultimately whether the
music strikes our brain as right, or the brain tells us something is amiss,
is not "objectively" measurable. The only way to objectify it is by
allowing humans to interpret it as music, and then to develop tests to try
to record that *subjective* response in ways that can generate some
*objective* results in the statistical sense. And there is the rub. It
demands context for the brain to interpret what is going on. Let me give
you a non-musical example that I use here before...about a year and a half
ago, I think.
Suppose you hear a split second of a car crash. That's all...half a second
of indecipherable noise. You wouldn't even know what it was. However, if
you heard a recording of street sounds, and auto approaching, a squeal of
tires, and then the crash, you would know what you were hearing. And if you
heard it through two different systems you could probably which one sounded
"most real". However, if all your heard were two snippets of sound of the
crash itself, my guess is your brain would be trying so hard to make sense
of what you were hearing you couldn't evaluate anything in the way of which
sounded most "real" because you didn't know what "real" was.
But, even then you'd still be unable to interpret that context unless you'd
heard a real crash on a real street. How many have except for a film or TV
show?
Something similar happens with music but even more complex. Because
scientist now know that the brain is hardwired to respond to this thing we
call "music", both rhythmically and emotionally.
They do? Why does the natural sound of loons crying on a lake or a rainstorm or
the sound of lake water or a stream get second billing?
Further the work done by
Oohashi et al (The Journal of Neurophysiology Vol. 83 No. 6 June 2000, pp.
3548-3558) indicated that this emotional response took place over time, as
much as twenty seconds of time, from the time of the sound. Presumable this
is the time it takes the brain to recognize and interpret the music as
pleasurable, unpleasurable, rhythmically coherent or incoherent, etc.
"Presumable"? You're just making presumptions that you believe will undo
extant evidence that's uncomfortable for you.
This fundamental fact means that you cannot measure "sound" and determine
its impact as "music". The factors affecting how we respond to music are
apparently very subtle and "time-based" and "harmony-based" and not static.
But a short burst comparison without much in the way of context for
recognition, relaxation, and response (which is the way most short-interval
testing is done) tends to short-circuit the process. This is the objection
must "subjectivists" have to ABX'ng in practice and why they question "null
results" that seem so at odds with so many people's otherwise fairly clear
perceptions of differences.
No; you're just responding to the results IMO because your "fairly clear
perceptions of differences." can't be verified with listening bias controls
implemented.
Oohashi et al indicate in the quoted article that they have confirmed this
speculation. That is, they have used short-interval comparisons of music,
and found "no difference" in ratings in line with accepted believe. But
when using "long-intervals" using the same stimuli and sequentially monadic
ratings, the achieved statistically significant differences in response to
the two stimuli.
You "amps is amps" people seem to want to ignore this finding, which is
pretty earthshaking and has nothing to do with whether you think the
"ultrasonic" portion of this test was done correctly or not, since
presumable the same stimulus was used in the precursor test (although to be
fair this should have been better documented in the article rather than
treated as almost a passing reference). This finding alone, if
substantiated by others, would rule out much of the abx and possibly most of
the dbt's done to date.
And, Tom, before you say it, I know dbt'ng doesn't *have* to be done that
way, but the fact is most of it has been done that way.
Let me refer you to "Flying Blind" (Audio, 1997) which confirms that short
intervals are the optimal method for detecting difference. You'll have to find
a better passing reference Harry.
Back to the main point; evaluating components is *not* hearing differences,
but evaluating how possible differences effect emotional and rhythmic
response from us as humans. There is a big difference. And the answer to
the "there have to be differences fist" response is....how do you not know
there aren't if the test itself tends to short circuit those responses.
Because the methods don't. Bias controls short-circuit non-sound and non-music
responses that have nothing to do with true stimulus differences.
This is why there have been requests for evidence of rigor in the testing
and for validation of the abx and abc/hr testing themselves versus other
forms of testing (for example the sequential proto-monadic used by Oohashi
et al which do purport to measure differences. it cannot just be assumed
away.
That's right; wishin' and hopin' and presumin' don't make for confideden
results that you and all the proponents never been able to verify with even the
simplest of bias controls implemented, simple as putting a blanket over the
amplifiers.
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