The above seems pretty weird to me with its apparent attempt to escape from the crux of the matter, which is whether resampling is or can be audible or not.
There seems to be plenty of evidence that while resampling has been on occasion done badly in the past, Similarly the usual kinds of resampling can be done today in a blameless way.
In short, its like just about every other kind of technology - a few dropped balls, and after a while a long history of doing it right.
There's only one "problem" with your assertion. Most of the industry standard programs that do sample rate conversions do in fact offer various options. For example, when I choose to resample a file in Izotope RX 3.0, I am asked to choose settings for "filter steepness", "cutoff shift" and "pre-ringing". The documentation describes how each affects the results; and, while there are default settings, there is no explicit statement as to which setting is "right" or "most neutral". Since the more extreme settings do in fact produce easily audible differences, and there is no claim as to which settings will be "actually correct", which setting should we be using - if we want a totally neutral conversion? So, even if I were to agree (for the sake of discussion) that a totally neutral and inaudible conversion process is in fact available today, which program - and which setting - should I use to get it? I've also seen comparisons where several files were converted - from and to the same sample rates - using different conversion programs, and, again, the results were audibly different. Now, arguably, there might be some choice of settings on each that would all produce the exact same result, but I don't know what it is. So, obviously, at least some "reputable" programs produce conversions at their default settings that are audibly different. If you want to assert that a totally neutral conversion is in fact possible, then you'll need to tell me which program does it, and... er... I guess we need to do a study to confirm that you're right. To put that in the context of my previous statement about test requirements: Before we can test whether differences in sample rates are themselves audible, first we need to determine what program - and what settings - we should use to create test samples that we can confirm are
OTHERWISE audibly identical.
However, to respond to one of your previous posts asking for my idea for a good test protocol...... here goes.....
HERE IS MY SUGGESTION FOR A TEST PROTOCOL - TO TEST THE AUDIBILITY OF DIFFERENCES IN SAMPLE RATE
First, we need to state our intent, and some of the problems we expect to have to overcome:
1) We're trying to prove whether differences in sample rate
ALONE are audible - specifically when we're talking about sample rates above 44k.
(So, for the sake of simplicity, lets limit it to one case: Are there audible differences between "the same content" when recorded at 16/44k and 24/96k?)
2) We aren't asking what percentage of people can hear such differences, or which equipment they're audible on, or with which sample content. The assertion is that the difference is
INAUDIBLE, so, if a single test subject can
RELIABLY AND CONSISTENTLY detect and note the difference on
ANY equipment, with
ANY test file, under
ANY listening condition, then we will have proven that there are audible differences. (And we're not asking whether our test subject can tell which is which, or which he or she prefers - simply whether they can detect a difference or not.)
3) We've acknowledged that at least some programs will
NOT give us a "perfect" conversion. Therefore, the fact that a certain observer can detect a difference with certain files will not be conclusive - because the audible difference may simply be an artifact of an imperfect (or "non-transparent") conversion.
4) We must acknowledge that we can't possibly test every combination of speaker, headphone, amplifier, test subject, and source material. Therefore, we need to find a way to minimize the possibility that we might get a null result simply because we chose equipment that isn't able to allow our test subjects to notice a difference that really exists.
5) Since some DACs "handle" different sample rates differently (different filters, different DSP processing, different oversampling ratios), we would like to rule that out as a factor. (What if someone hears a difference because the particular DAC he used applies a different filter to 44k files and 96k files, and the difference in those filters is audible.)
Since we don't have an unlimited budget to purchase every DAC, headphone, amp, and speaker ever made, but we still need to make a fair attempt to avoid "missing" the one combination that might prove the case, I suggest we leverage the idea of "motivated self-selected test subjects".
So here's my protocol.
1) First we select one or more conversion programs that we "agree" are "neutral". Since you are the one claiming that several modern programs meet this requirement, I'll defer to your judgment on this (or we can enlist some "industry experts" and ask them).
2) Then we secure a reasonable selection of "high quality 24/96k content. We can again ask some industry experts to tell us which content they consider to be "critical" or "difficult" (which content they expect a difference to be most likely with).
3) We will then, of course, generate a selection of file pairs - each consisting of the same content at 16/44k and 24/96k.
4) We will now offer ten of these pairs for public download, so that people can try them for themselves, along with an offer/challenge. (This will serve both to solve our "equipment problem", to self-select interested individuals, and to provide motivation both for individuals to participate, and to self-screen themselves to avoid wasting our time.)
The challenge will be that, if an individual is convinced that they can in fact hear a difference, using their own equipment, and using the files we provided, they will be invited to participate in the study. They will be expected to pay their own expenses to transport themselves to the study location, and will
NOT receive any payment simply for participating. However, if they can successfully identify the 24/96k version of the test files we provide 90% of the time, that will be considered "a significant result" - and, if they can demonstrate such a result, they will be reimbursed for their travel expenses, and will be given a $1000 cash prize. (We have allowed the "claimants" to pick - and provide - their own equipment; we have given them an incentive both to participate and to try their best to succeed, and we have provided them with an incentive to self-screen, and so to not waste our time with vague and specious claims.) We could add the option for them to provide their own 24/96k file, which we would then convert using
OUR "known neutral" conversion software, and include in their test run.
Note that, since the "actual test" will be run by us, there will be no opportunity for the participants to "cheat", yet we have also provided them with sufficient motivation that we can expect their "best effort". And, since we have invited participants to provide their own equipment, nobody can claim that the equipment we provided "isn't revealing enough", or that we have otherwise biased the test to fail. (We can't claim to have tried all equipment, or all test conditions, but we have at least made a "fair try" to cover the equipment that the folks who claim to hear a difference themselves claim is "most revealing".)
* Incidentally, I see one thing that I've
FAILED to account for.... #5 in my "intents and problems" section - the possibility that the particular DAC chosen by one test subject handles files of different sample rates differently, and so introduces audible differences between them when they're played that aren't due to the content itself or to the sample rate itself. This is actually a common problem with NOS DACs, many of which have a frequency response that is -3 dB at the Nyquist frequency (so they're -3 dB at 20 kHz with 44k files, but -3 dB at 48k with 96k files, which difference is clearly audible as a high-frequency roll off with 44k files, even though not strictly due to the difference in sample rate itself). There may also be other DACs out there which introduce similar, but less obvious, differences. [Ooops.... I may have just demonstrated that even files that really are "information identical", but at different sample rates, will in fact sound audibly very different - with some DACs. Is it really reasonable to "arbitrarily" exclude those DACs from our study? This may make what we're trying to prove somewhat more complicated... or we may need to restate our intent to sidestep it. Now you see why designing GOOD test protocols can be complicated... and people make whole careers out of it
]