sort of global response: we have to determine what we're trying to achieve. best measurements or sort of realistic measurement? because holding the IEM in place is something that doesn't necessarily happens in our ears even when the shell is securely fit on part of the pinna and ear canal, all that stuff is flexible.
same for the idea of not using tips. for anybody who needs to make repeated measurements that must achieve the same response, obviously getting rid of the tips is the best approach. Etymotic has a sort of mold where they insert the IEM without tips to measure and match the pairs of the er4 series, and probably to test a lot of stuff on the other models. but the reliable, highly repeatable response we get is not what an actual ear will get. and that to me is a problem. I'm well aware that even the IEC standards are in the end practical choices, some even suspiciously arbitrary IMO, but at least those are references that most people have learned to interpret subjectively(with more or less accuracy). I personally feel that there is value in all those years of habits. if a new better standard comes along and is accessible to us amateur nerds, I'm up for it, but it needs to be something accepted by most people, or we need to have such a massive output of measurements that we can become our own reference, like Tyll did with innerfidelity, like crinacle is doing right now. we accept that their measurements might not mean much in term of standard, but they provide big enough samples of measurements for us to get the relevant relative variations compared to some IEM we have used ourselves.
@hakuzen the most successful changes for me in term of vibration:
- delay the measurement by 2 or 3 seconds in REW, click and move away. or put the mouse on a different desk and stay away ^_^
- measure from 10 or 15Hz instead of 20Hz. I still only look at and show from 20 to 20K, but sometimes it avoids some wiggly artifacts in the subs. no idea if that's due to my gears or if it's something that sometimes happens in REW? same thing with measuring impedance, on rare occasion the impedance curve takes a dive in the upper range, and if I do it again, it rises(if BA), or does whatever it's supposed to measure. I don't seem to be changing anything, so I assume it could be REW. I remember seeing Purrin show such an impedance response that wasn't right in the treble, so I assume it might happen to others too. for that beyond doing several measurements, I'm not sure how to avoid it from happening(but it's super rare for me anyway).
- using a fanless computer. I only do it when I'm really looking for something super specific, because the fanless one I have was crap when it was new, and that was years ago^_^. it's just so slow I go mad from using it. so I usually measure with my rather noisy but responsive one as for FR at least, it's irrelevant so long as I measure a signal in the 80-90dB SPL. but for distortions, in my case it changes everything. I've done stuff to reduce the noise coming from my regular computer too, with yoga brick, acoustic panels, pillows, etc, but none of that can stop low frequencies. so to my ears it's pretty quiet, but my mics disagree ^_^.
- electrical pollution. some gears are just more sensitive than others, but it seems pretty common to have some little 50 or 60Hz noise, or other stuff when some equipment is running in the house. my personal nemesis is my fridge. if it starts running while I measure stuff, noise and distortion levels increase instantly.
- in the dead of the night is always where I got my cleanest measurements, because people sleep. even from an electrical point of view things are just better for me usually after 1AM. again, that doesn't matter for FR, only for stuff measured some 40dB below signal and lower.
- try to feed the mic with different sources. when I started this, I was always feeding my Vibro Veritas with a really noisy and crappy soundcard from my laptop, and it's only when I got other mics requiring different sources/plugs, that I realized how crappy the laptop's DC powering the mics really was. I made an adapter to still be able to use most stuff from the laptop, and that was my wake up call. virtually anything was cleaner, my tablet, phone, some batteries, they all were a lot cleaner. now I mostly use a mic that requires 48V of phantom power, so I don't really have a choice. but for the dayton it might be worth trying a few devices just in case.
well I guess we could also just have proper gears and clean quiet room, but I at least will never have that.
(Another development in some of the newer models is trying to account for the fact that the human eardrum isn't normal to the axis of the canal, but rather at an angle. Probably there's some evolutionary advantage to the latter.) But I'd bet money the overwhelming effect comes from the longitudinal mode, i.e., the total distance the acoustic wave has to travel from driver to eardrum.
