Hi
@Sean Olive, great to see you on the forum, and thanks for elaborating on my earlier post
While we're in conversation, I hope you don't mind me asking you a couple of questions about the heaphone target you nd Welti derived?
Firstly, I wonder why the starting point used in your 2015 study with Welti was that of a pair of loudspeakers equalised to have a flat steady-state response, and not a flat diffuse-field response? Also, did you conduct research indicating to what extent the in-ear response differed for a pair of loudspeakers equalised flat in-room vs. a flat diffuse-field response? If so, what were the differences? (I.e. perhaps the two responses when measured at the ears are essentially the same, which actually seems plausible for measurements performed beyond the room's critical distance).
Secondly, I wonder if you have a theory as to whether (and if so, how/why) specific design characteristics of a given headphone may affect a given listener's preferred target curve (and by corollary, the average listener's preferred curve).
This second question is informed by two factors. Firstly, your research suggests that the preferred curve is different for IEMs than it is for headphones. And secondly, my (obviously limited) personal experience is that larger open-backed phones tend to sound more bass-heavy than both IEMs and smaller closed-backed phones when EQ'd to the same target response. I speculate that this may be due to the differing accoustic impedances in the volume of air between driver and eardrum, and/or differeing driver-to-eardrum distances (assuming, of course, that my own headphones do not measure significantly differently to those on which the correction curves I've used were based).