Well… I’d like to think that the exclusion of the unwashed masses in the whole ‘trained vs untrained’ thing is a bit of a misnomer, or what we might take from that should probably be scrutinized a bit.
To put it bluntly, I don’t think we should so easily put audiophiles into the ‘trained listener’ category, and if anything we’re more likely to muddy the results than contribute to a clear outcome. Moreover, the whole ‘trained listener’ thing requires quite a bit of consideration as well, as I remember that what constituted ‘trained’ was a minor sticking point when reading through the research and caused me to raise my eyebrows a bit. But, at the end of the day this is the best we have for publicly available research on this topic, so it’s what we go with. Perhaps a better parsing of listener types should be something along the lines of “those who strongly give a shit about tonality”, vs “those who only mildly give a shit or are otherwise indifferent”.
This was also the initial concept behind the Harman Combined target, in the sense that I felt it was a bit more appropriate for picky listeners when it comes to bass to treble delta than 2018. I could’ve just gone with 2013 but I know a lot of us find that to be too shouty at 3khz, myself included, and I also suspect this is one of the reasons for the treble lift in 2018, since, as you increase the treble above 3khz, the glare goes away with lower harmonics not dominating as much over upper ones. Also keep in mind that the region above 10khz is unreadable due to measurement artifacts, so it shouldn’t dip down there like it does to that extent.
There is also another element to this, which is that Harman is smoothed to 1/2 octave. And if you look at Harman in-room and unsmoothed DF, they’re fairly close there with the difference coming down to the Harman conditions, like the specific Revel speakers and that room. Overall ear gain level for an unsmoothed target would be higher around 3khz than what we use too, and I think this is a bit of an issue.
My take on this right now is that this is probably at the edge of what’s tolerable for folks. Like, depending on the ear, you may have a different tolerance for that region, but also we have to consider that for certain types of music and recordings, that high of ear gain just isn’t going to work. So either we bite the bullet on bad recordings and just say too bad for more aggressive music, or we aim to be a bit more conservative in that region for the benefit of versatility - again, just a thought. We don’t have that built into anything yet on the 5128, but it’s up for discussion.
The nice thing about using DF plus slope is that you get a better view of what the treble should be in relation to the highest part of the ear gain, which so far has yielded a massive improvement to treble timbre. But, we’re of course also discovering that this isn’t the same across different headphones. So, whatever happens we’ll need to build in boundaries around the target to reflect those differences - and also the fact that people have different heads/ears.