I can hear the difference, about half the time, but it just doesn't register with me, because my brain considers both sounds to be "i".
In my native language, for example, I grew up in an area where many people pronounce some "i" like "ы" rather than "и". I personally don't, but I hardly even notice it if somebody else does. To my brain, и/ы is an artificial difference that I just don't notice unless I really focus on it.
I know that it is important in Russian, but it takes some time to get used to.
I took a 2.5 year break in my (rather relaxed) Russian studies, so I found that I had lost the "feeling" for that, and I remember making spelling mistakes with it even before my break (in flaschards). I never memorised the rule because I assumed it was fall into place naturally, but somehow that never fully happened. When it's explained, the logic is complex.
I have the same problem with "ь". Sometimes it's obvious where it's needed, but quite often, when trying to spell a word, I have no idea whether it's needed or not. It's really frustrating. This so called difference is just barely noticeable as far as I'm concerned.
It's a bit like with the bizzare peculiarities of English spelling, only in my case I am used to the bizarre nature of English spelling and I don't notice it anymore.
No doubt, with practice and experience Russian spelling becomes second nature, but I am not there yet. But it's extra challenging because the silent sounds and some sounds that don't exist in other languages.
Basically it's the same problem as you probably encountered with definite articles; you probably thought "What the heck is that needed for? What a nuisance!" - but to me that is as obvious as the difference between и and ы is - requires zero thought.
i understand several European languages quite well, but that's just because it's quite easy, you can just glide along and pick things up with little effort. Russian needs work, effort and using your brain a bit.No freebies....
In some cases it's totally obvious, it's not as if I can't hear it.
But there are also these exceptions where you think it'd be one, but it's the other....
Other than those two, I love Russian spelling - it's really phonetic.
If you are going to be fair, compared with English spelling, Russian spelling is more logic - the challenges are these two things that are different.
Anyone who wanted to produce a course in Russian for Europeans and English speakers should have a special chapter each just for drilling in the silent signs and the sche/sh sounds and their spelling rules. It would be effort well spent.
I'm tired of doing my flashcards right, then missing on the spelling.