You have eliminated important caveats in repeating that marketing talking point. That assertion is based on a limited study where nearly 1/3 of the subjects were excluded from the project because their protocol failed in capturing a reliable measurement.
I will say this again, if you understand the actual causes of variation in ear Z, you will see that it is by no means likely that excluding subjects has biased the trends of the ear Z here - there are a finite number of mechanisms of error, and their traits are pretty obvious in the data. Søren and co have excluded the data showing these predictable error mechanisms - again, I'd allege that low-frequency leak, visible as a higher order rise in the equivalent volume dimensions, is probably the major cause, but I didn't work on this paper, so that's conjecture
All studies are of course limited - this may be said of pretty much anything under the sun. This study is, however, the more comprehensive study of human ear impedance, and it accounts for the largest range of confounding variables - it is "the state of the art", such as it presently exists, unless I've missed a more recent publication (which I'd be very eager to read if I have - please link it).
Look at those incredibly tall error bars (light green) that are even falling out of the bottom of the graph at just 6 kHz! The fact that you can compute a mean out of them doesn't let you out of the quandary that you are leaving a ton of listeners behind. So what that the dip at 14 kHz shouldn't be as deep as it is on a stock 711 fixture. You can't quantify much in that region anyway.
The variation at 6khz is pretty evidently because that node wasn't the alignment point used in the paper
however, that's also a product of the volume length, which, as you note, will inevitably vary both with insertion earphones (because of fit variation) and with open canals (because canal length varies). It's helpful to look at the causation of variation when we consider if it's problematic or not.
We want to predict listener preference and tonality of response and for that, the findings of this study shows how bad the situation is due to highly variable aspects of human ear canals. It is a miracle that Harman managed to make some sense out of these measurements after much work and refinement.
I'm departing this conversation, but rhetorically I have to ask, what
is the sense and work you see in the Harman work, if you, as previously discussed, completely discount the predictive models? What differentiates Olive's work from ex.
Fleischmann or
Lorho? Is it simply the volume of papers and listeners? It would seem that you treat (some unspecified subset of, not including the bits on predictive modeling) Sean's work differently than other works in this field in that respect, but I'm not entirely clear on what it is that makes you more prone to doubt some papers than others.
What this means is that none of these measurements at higher frequencies have much measure of accuracy. To claim that a match to "human Z" has been found where the very experiment shows human impedance is all over the place means your statement is just pure marketing.
This seems like it misunderstands
the fundamental cause of variation in Z in this band, which is kind of a recurring theme here, but
deterministic variations are not the same thing as random noise.
There is no question in my mind that these fixtures are purchased in a competitive race to what other reviewers are doing with nary a thought as to whether they are helpful in answering any useful questions after you spend some $40,000 on it. It is height of subjectivism to spend money first and figure out the answer second. Of all people, I am the one that wants the best there is when it comes to measurements as to reduce the amount of criticism over them. But here we are folks jumping on a new fixture where questions are front and center and answers are just repeating marketing lines.
I suppose I can't stop you from adopting this framing - and, certainly, if one wishes to apply your own style of "painting bad motives onto your interlocutor", it's quite beneficial to you, as a non-5128-owner, to adopt this stance - but the very concept of "the best there is" regarding HATS is a bit misleading to begin with, and I think that your anchoring to that premise is part of why you have a weird complex about people talking about the technical merits of the 5128. There are legitimately meaningful issues with all artificial ears and heads, documented across the lit - including, recently, by Sean's comparison with blocked meatus microphones - when it comes to predicting in situ response on human heads. No one head is a canonical truth of the subjective experience every user will have with a headphone, and indeed, it's very likely that we must develop metrics that account to some degree for variation here (in the same way that DI predicts, to an extent, sensitivity to room variation) if we want to improve in the long run on Sean's models (good though their fit generally is).
The only thing I need to look at is that you have taken a consulting position to headphones.com and put forward as the expert witness on why they have purchased the 5128. If this is wrong you need to come out clearly and properly state that purchasing a 5128 for headphone review is a mistake. If you don't, and keep defending it by throwing papers at people while leaving out key detail, then I am going to call you on both fronts.
Ironically, the commanding majority of the consulting I do for Headphones.com is helping them interface with some Chinese manufacturers I know - I don't think I was even
in any of the content they put out regarding the 5128, and I'm posting here on my own time (indeed, I got a message at some point along this thread to the effect of "you know that we're not paying you to argue on the internet, right?") and with my own motivations.
However no, I do not need to state that purchasing the 5128 for headphone review is a mistake, and no amount of hamhanded attempts to force that dichotomy will do so, because
I strongly supported buying the 5128, and am glad that firms like RTings have added it as well. What
would have been a mistake is saying "all 60318-4 measurements are fundamentally useless, ignore all of them, we're throwing away our 43AGs, we'll only do 5128 measurements from now on", and I'll happily condemn the hypothetical alternative timeline nega-@Resolve that said that in universe 616. However here, in the reality that actually occurred, adding additional data from an additional pinna
alone would be justification to purchase a second HATS, which was
indeed part of my specific argument for buying it, with the added benefit of giving us a picture of the behavior of high acoustic Z designs with more accurate loading.
This strange premise that there is simply a "best ear" which should be used to the exclusion of all others is, frankly, an infantile assumption that everyone is buying these tools in an attempt to defame all their "competition" - you may be looking for a reason to say that other people's data is untrustworthy, but that isn't the motivation of everyone who buys a new metrological tool. Your
repeated insinuations and outright statements that I'm some sort of paid shill for holding a position which I've demonstrably held since before I got one red dime from Headphones.com (and, sadly, I have yet to be paid
at all by Hottinger Brüel & Kjær) and attempts to pin on me,
@Resolve, and everyone who says something positive about the 5128 some sort of narrative that 60318-4 measurements are useless or should be disregarded out of hand, say everything about the degree of insecurity and incivility with which you're approaching this.
I suspect you are having some sort of protracted, imaginary argument with Jude Mansilla or someone else who you dislike who was very pro the 5128 - I don't particularly care, I'm not going to be the stress ball for it. I have attempted to explain to you, at length, the
real but not disqualifying to extant systems technical merits of the 5128, the relative issues which exist with
all headphone metrology, and why I'm quite pleased that both KB501x and Type 4620 data (and, hopefully soon, data from the new HMS, and its distinct pinnae) is increasingly available, and my hopes for where we can go with data from multiple pinnae, and with a more realistic ear load for in-ear headphones (particularly, ironically, at low frequency - I feel like people keep ignoring that, but that's actually where the 5128 is meaningfully more interesting IMO). I've attempted to do this civilly, and I haven't accused you of financial motivations, petty vainglory, or any of the other immediate reactions that your inane and bad-faith responses provoked, because
we aren't even on opposite sides here - this is a "conflict" that you have manufactured between the 43AG/45CA and the 5128, and I have refused - and continue to refuse - to make it real, because it isn't, at least for me, for Headphones.com, for Crinacle, and for every other interested party I'm personally connected to who has worked with the 5128 which I am personally familiar with (Linus Media Group, HypeTheSonics, RTings).
You have created a pointless argument here and made it pointlessly uncivil, and produced a wealth of ammunition for everyone out there who wants to paint the pursuit of scientific audio as venal and self-interested here. I have a distinct flashback to your past conflicts with Erin, Arny (RIP), and heaven knows how many others. I am no longer feeling like taking the high road, so I will be taking my leave instead - you will, naturally, have the last word, as is your wont.