For me, the pronunciation of some words that end with 'ы' sound like they end with 'э', like 'газеты' or 'журналы', but others don't, like 'столы'.
What is the reason for this? Do we say always 'э' when it 'ы' is unstressed and at the end of the word? Would we otherwise say 'ы'?
Well, it's easy to check. So, you are saying that ы sound like э so why not just substitute and repeat two-three times, loud and clear and slowly: газетэ and журналэ. Does it sound right to you - well, it's clearly not.
What you do actually hear is that ы is reduced when it's not under stress (like in столы) - you hear a very short vowel which is still not э nevertheless.
In fact there's a name for that particular vowel - it's called шва. In Russian it exists only in this ultrashort form that one can hear only in unstressed form - that's the reason why this vowel, which is actually one of the most frequent in Russian is not well known - native speakers just don't realize they pronounce it at all.
Whether we can treat this vowel as sort of short ы or э is subject to discussion - it's complicated - in fact there are some linguists who don't believe we have such phoneme in Russian (they claim it to be just an indicator that preceding consonant is non-palatalized), some others don't agree with them - check out this question for instance.
But what we can state though is that reduced variables are so short that it's extremely hard to tell them apart, that's for sure. It's similar to how жена sort of sounds like жына with a very short ы. Or и. Or э - you got the idea :)
