You'd be really surprised (maybe) that what really reveals your Slavic accent is Vowels Exactly vowels can tell a native speaker that something is off Consonants aren't a big deal, honestly. But English vowels are more subtle and harder to grasp, and they require much more time to train and master. And even after mastering them, Slavic o and u (and not only) will still slip off your tongue accidentally if you don't live in an English speaking country,, listen to native speech and communicate in English 24/7 Interestingly, i started to clearly identify the shwa and weak u sounds not long ago, allegedly a couple of years back. I hear and differentiate sounds very well now but that took a lot of time. So, the conclusion is - mind your vowels and don't underestimate them if you wanna sound natural and truly American