On Apr 28, 12:02 pm, Edmund <nom...@[EMAIL PROTECTED]
> wrote:
>>> Long time ago, not with young people but older where
>>> tested. They where tested and all where complete
>>> deaf over 14000 Hz. So they played music and
>>> switched a filter on and off at 16000Hz. ALL of
>>> them could tell the difference!
>> Who? When? How? Can you site a particular reference,
>> or is this just memory of an anecdotal tale?
>
> It is something I read 20 or even 30 years ago, don't ask
> me for details :-)
But you stated with such certainty, bordering on
authority. Now, it seems, you don't rmember any
details, you can't even say who did the study. That
might lead on to suspect that it might be nothing
more than third-hand urban legend.
I was active on the field 20-30 years ago and such
a study with such defintiive, nearly earth-shaking
results would have been VERY hard to miss. It certainly
is not to be found in any of the professional literature.
Does it even exist?
>> In other words, we have two examples of tests
>> which have a fundamental flaw in the methodology,
>> and do NOT, as you might think, illustrate the
>> significance of ultrasonic bandwidth.
>
> One detail I remember was the individual testing was done by
> sine waves, which showed that non of the members heard anything
> (at given level ) over 14000 Hz, most of them did a lot worse.
> The filter test was done while playing music.
You seem to have missed the point: we have before us
two classic and oft-used examples of tests that are cited
as "proving" that information above the ultrasonic cutoff
can be detected by the human auditory system. Both
of these methods are flawed and prove nothing.
The method you cited, switching a 16 kHz low-pass filter
in and out, is significantly flawed. 20-30 years ago, it
was almost certainly a purely analog filter. At 16 kHz,
it's already 3 dB down. Assume a maximally-flat 2nd-order
low pass filter. Here is its response:
2000 -0.03
2500 -0.05
3150 -0.09
4000 -0.14
5000 -0.23
6300 -0.38
8000 -0.64
10000 -1.06
12500 -1.76
15900 -3.02
20000 -4.84
Now, yes, the filter is down -3dB at 16kHz, as per
spec, but it's also down 1.76 dB at 12 kHz, which
the subjects COULD hear, according to your "test",
it's down 1 dB at 10 kHz, and it has arguably audible
effects down to 5 kHz.
How does such a test, which has real audible effects
BELOW 16 kHz, prove that information ABOVE 16 kHz
is audible? (hint: it can't: the test is fatally flawed from
the get-go).
And this is based on a mathematically filter: a physical
respresentation is not likely to be as good.
How does one now that the filter itself is not adding
other audible artifacts that the listeners were cueing
on (answer: you don't: you have no details of the test).
All in all, I think this 20- ro 30-year old test can be
simply dicounted as being of no value in proving
anything at all.
>> And can you prove conclusively that the CD layer
>> and the SACD layer were, to begin with, exactly
>> the same save for the bandwidth? For example,
>> it is not infrequently the case where the CD layer
>> and SACD layers can be made with two different
>> sets of masters.
>
> No I don't know about that, I assume they used the very same,
> why would they use or even make different masters?
Why would you assume they were the saem?
There are PLENTY of reasons, valid and not so valid, why
the would be different:
* Part of the function of mastering is to "optimize" (in
the best case) or otherwise "adjust" the recording
to fit the particular medium. That would result in
different end ,asters for CD, SACD, DSD, LP, and
so on. They would most definitely NOT be the same
because the media are different.
* Some producers have a stake in the outcome. If
they want to make sure their SACD sales are up,
they'll make the SACD quirte audibly different
than the CD. You think these people are in business
for YOUR benefit?
* Two entirely diffeent people may have been responsible
for mastering the two media, with different results.
* The SACD came first, and the CD layer was an
afterthought, so little effort was made to make
the CD layer was done right.
* If the SACD and CD layer REALLY DID sound the
same, what reason would their be for people to
replace their CD collection with SACDs?
That and 20 other reasons.
>>> Some time ago :-) I have compared the CD
>>> with good vinyl, no doubt the vinyl sounded
>>> better although the vinyl had the additional vinyl
> >> problems.
>
>> That, if you're at all serious, is an interesting comment,
>> since, for the most part, the practical bandwidth of vinyl
>> is less than that of CD, due to mechnical limitations in
>> medium. And that's even more curious in light of the
>> fact that most recordings have significant
>> bandwidth limitations before they even hit the final stage.
>
> If that is a fact and there are no exceptions
> I wonder what kind of effects are at work then.
Again, PLENTY of reasons.
The mastering process to produse an LP stamper results
in quite different audio than the mastering process to
produce the corresponding CD stamper. FOr example, to
prevent excessive groove excursion and thus reduce
the amount of available real estate on the LP, low frequencies
are compressed and, often, partially summed to mono.
Because the cutting and playback stylus must occupy
some non-infinitesimal volume, linnear superposition
does not hold, with a result of higher distortion in LPs.
The dynamic range of LPs is compressed, noise floor is
higher.
The original mastering of the LP is unsuitable for CD,
and vice versa, therefore, the mastering process for a cd
is VASTLY different than for the lp.
All of these and MANY other reasons make it a certainty
that NO LP is going to sound like the CD. That's a
matter of physical fact.
Which sounds better is a matter of personal preference
and judgement.
If someone were to come to you and want you to tell
if two media sound the same, you can save a LOT of time
by simply saying "they don't."
Which sounds better? To me, the one I like.
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