It’s one of the reasons IEMs are a problem. Headphones have variability problems too, but they are a little bit more observable. And, at the very least there’s some specific pinna interaction available in measurements, and length mode resonances aren’t a problem.
IMO you have two choices as an IEM designer:
- Err on the side of caution for potential problem areas for people even if you don’t personally have them
- Recognize that you can’t please everyone and just commit to what you like in a way you think will work for most people.
Ideally you do what @veebee did here and just have different versions built on a theme. I’d personally love for something in between, but as a design strategy, I think it’s totally reasonable.
Now, as a consumer, if you have no way of knowing how you’re going to hear something and you have to blind buy, there is actually something you can do. If you already have a set of IEMs that you use, ideally something that measures reasonably. Do manual tone gen with a tool like Owliophile to identify the dominant length mode resonance for you with that product, it’ll likely be anywhere from 6khz to 9khz.
There’s no guarantee you’ll hear it at all, and it can be in a different spot depending on how the IEM fits in the ear, but it’s at least something you can try. If you do hear that resonance closer to 8 or 9khz there’s a good chance Lumen will work for you. If you hear it at 6khz, then that may be an issue. Again this is a very crude and unpredictable test, but it’s at least a starting point to better understand your anatomy.