Quote Originally Posted by birdeen's call View Post
Thanks! This is a very interesting discovery to me. I was always told that English didn't have the feature of devoicing voiced consonants word-finally (which is present in Polish - in isolated words). But it seems it happens in some cases. In Polish, we also do not devoice our consonants when a vowel follows.
Phoneticians will tell us that there are a lot more variations in allophones than most of us, including teachers, are aware of. The very slight differences are not really important (if they were, we'd be more aware of them), though they explain in part why non-native accents in English are so fiendishly difficult to eradicate.

Each individual 'mispronunciation' cannot be detected by most native speakers, but the cumulative effect makes the speech of all but a gifted few advanced learners of English slightly 'off'.