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A new target?
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digitalfrost
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Read further into that thread... it's not that simple.
Again, there's a lot more to it than that, and I'd encourage you to read through the rest of the discussion there. What he's talking about in the second bit is to do with their recent presentation that involved mannequin heads vs actual humans with canal blocked in-ear mics, and what they found is that mannequin heads in general aren't necessarily more accurate representations of humans, and this is in part due to them being more difficult to achieve a seal than on humans (and also some overestimations above 1khz as well). But that doesn't mean the 5128 isn't more 'humanlike' or somehow inferior to GRAS systems, merely that mannequin heads != closer results to measurements on humans. Now, if you look at the presentation... some of those mannequin 'prints' are... questionable, and likely don't have the same pinna deformation of official measurement rigs, and unfortunately it's not stated which result corresponds to which mannequin. So we'll need to do similar testing with in-ear mics on both humans and the 5128, and this is in part why our target is still a work in progress.
The first part is definitely an important note, but this is also the reason why their 5128 Harman target stop-gap isn't suitable for development of an actual reference curve. Their own version of it is based on the measured delta for different headphones across the rigs, and this doesn't work because headphones behave differently on different heads, which is the reason for Sean's point here. In our case, using DF plus slope at least allows us to apply the same principle to different rigs, making them at least comparable - even though not predicted to look identical when compensated.
Here's some of the rest of the discussion and responses from Blaine:
I already did.
I know.
I don't think anyone's saying it's inferior, just that there's no solid evidence it's superior, producing a more accurate approximation of the response on real heads than GRAS simulators.
I did. The presentation also shows none of the mannequin heads (of which the 5128 was one) did any better than flat plate GRAS rigs (45CA) with anthropomorphic pinnae (official GRAS KB5000 and Welti's custom ones which the Harman target is based on). It's all very well the 5128's ear canal being more anthropomorphic with a more accurate acoustic impedance, and looking 'humanlike', but if the head shape and very importantly hardness are all wrong resulting in excessive leakage and unrealistic reflections this is moot. That B&K (and GRAS) have completely failed to address the latter is baffling. Looks like you might need that skin-like ham for all your 5128 measurements after all
Testing on 2 (or even 3) subjects won't be enough. Sean's data above was from 15 subjects. The fact is you're not going to get as statistically robust results as Harman's multiple double-blind listening preference tests over the years that led them to their target.
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Summing up: mixing difuse field with sloping response that comes from a flat speaker in a room. Pretty much what I have described below.
"Sloped neutral" target curves for headphones and IEMs?
Some days ago I was reading reviews of headphones and IEMs, and their frequency responses compared against a "neutral" target curve, and that got me thinking... Contrary to a "preference" target curve, a "neutral" target curve, as far as I know, is defined by using a head (+torso?) simulator...
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Which is why we include the outcomes of the research for the target. And yeah, we're intending to do more in-ear mic measurements in general, even for evaluations from different people, but we can also find out fairly quickly if we need to cover the 5128 with ham haha.
And as a consequence, imo, no way a flat measuring bass IEM like the SR Etymotics are representative of sloped response of speakers in a room, which should be the gold standard.
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Again we come back to the elephant in the room, the lack of a singular “standard” that can be utilized for more realistic representation of measurements and sound is a cause for so many competing “standards”.
Yeah, and it's still a bit unclear as to why there's a preference for an even stronger tilt in IEMs. There's an argument it's down to psychoacoustics... but I'm not sure.
You also need to consider the SLD effect: acoustic sources at different distances from the ear are perceived to sound differently even if the measured response is the same. See Theile's seminal paper. Then there's the relative lack of tactile bass from headphones (and none at all from IEMs, which could, at least partially, explain the higher preferred bass for them) compared to speakers which needs to be compensated for. These are both reasons why preference listening tests are needed to arrive at the target, just as Harman have done.
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